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02a6eb2ebc229c2fc60d2eee2743416d2c597eba
sqlite/src/select.c
T
drh 4388522561 In ORDER BY LIMIT queries, try to evaluate the ORDER BY terms first, and it 
it becomes clear that the row will not come in under the LIMIT, then skip
evaluation of the other columns.

FossilOrigin-Name: c381f0ea57002a264fd958b28e4921cb9c9e73a10fb592f6bb64e6bc9bd16d39
2018-05-03 23:20:06 +00:00

6351 lines
228 KiB
C
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/*
** 2001 September 15
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
*/
#include "sqliteInt.h"
/*
** Trace output macros
*/
#if SELECTTRACE_ENABLED
/***/ int sqlite3SelectTrace = 0;
# define SELECTTRACE(K,P,S,X) \
if(sqlite3SelectTrace&(K)) \
sqlite3DebugPrintf("%s/%d/%p: ",(S)->zSelName,(P)->addrExplain,(S)),\
sqlite3DebugPrintf X
#else
# define SELECTTRACE(K,P,S,X)
#endif
/*
** An instance of the following object is used to record information about
** how to process the DISTINCT keyword, to simplify passing that information
** into the selectInnerLoop() routine.
*/
typedef struct DistinctCtx DistinctCtx;
struct DistinctCtx {
u8 isTnct; /* True if the DISTINCT keyword is present */
u8 eTnctType; /* One of the WHERE_DISTINCT_* operators */
int tabTnct; /* Ephemeral table used for DISTINCT processing */
int addrTnct; /* Address of OP_OpenEphemeral opcode for tabTnct */
};
/*
** An instance of the following object is used to record information about
** the ORDER BY (or GROUP BY) clause of query is being coded.
**
** The aDefer[] array is used by the sorter-references optimization. For
** example, assuming there is no index that can be used for the ORDER BY,
** for the query:
**
** SELECT a, bigblob FROM t1 ORDER BY a LIMIT 10;
**
** it may be more efficient to add just the "a" values to the sorter, and
** retrieve the associated "bigblob" values directly from table t1 as the
** 10 smallest "a" values are extracted from the sorter.
**
** When the sorter-reference optimization is used, there is one entry in the
** aDefer[] array for each database table that may be read as values are
** extracted from the sorter.
*/
typedef struct SortCtx SortCtx;
struct SortCtx {
ExprList *pOrderBy; /* The ORDER BY (or GROUP BY clause) */
int nOBSat; /* Number of ORDER BY terms satisfied by indices */
int iECursor; /* Cursor number for the sorter */
int regReturn; /* Register holding block-output return address */
int labelBkOut; /* Start label for the block-output subroutine */
int addrSortIndex; /* Address of the OP_SorterOpen or OP_OpenEphemeral */
int labelDone; /* Jump here when done, ex: LIMIT reached */
u8 sortFlags; /* Zero or more SORTFLAG_* bits */
u8 bOrderedInnerLoop; /* ORDER BY correctly sorts the inner loop */
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
u8 nDefer; /* Number of valid entries in aDefer[] */
struct DeferredCsr {
Table *pTab; /* Table definition */
int iCsr; /* Cursor number for table */
int nKey; /* Number of PK columns for table pTab (>=1) */
} aDefer[4];
#endif
struct RowLoadInfo *pDeferredRowLoad; /* Deferred row loading info or NULL */
};
#define SORTFLAG_UseSorter 0x01 /* Use SorterOpen instead of OpenEphemeral */
/*
** Delete all the content of a Select structure. Deallocate the structure
** itself only if bFree is true.
*/
static void clearSelect(sqlite3 *db, Select *p, int bFree){
while( p ){
Select *pPrior = p->pPrior;
sqlite3ExprListDelete(db, p->pEList);
sqlite3SrcListDelete(db, p->pSrc);
sqlite3ExprDelete(db, p->pWhere);
sqlite3ExprListDelete(db, p->pGroupBy);
sqlite3ExprDelete(db, p->pHaving);
sqlite3ExprListDelete(db, p->pOrderBy);
sqlite3ExprDelete(db, p->pLimit);
if( OK_IF_ALWAYS_TRUE(p->pWith) ) sqlite3WithDelete(db, p->pWith);
if( bFree ) sqlite3DbFreeNN(db, p);
p = pPrior;
bFree = 1;
}
}
/*
** Initialize a SelectDest structure.
*/
void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){
pDest->eDest = (u8)eDest;
pDest->iSDParm = iParm;
pDest->zAffSdst = 0;
pDest->iSdst = 0;
pDest->nSdst = 0;
}
/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqlite3SelectNew(
Parse *pParse, /* Parsing context */
ExprList *pEList, /* which columns to include in the result */
SrcList *pSrc, /* the FROM clause -- which tables to scan */
Expr *pWhere, /* the WHERE clause */
ExprList *pGroupBy, /* the GROUP BY clause */
Expr *pHaving, /* the HAVING clause */
ExprList *pOrderBy, /* the ORDER BY clause */
u32 selFlags, /* Flag parameters, such as SF_Distinct */
Expr *pLimit /* LIMIT value. NULL means not used */
){
Select *pNew;
Select standin;
pNew = sqlite3DbMallocRawNN(pParse->db, sizeof(*pNew) );
if( pNew==0 ){
assert( pParse->db->mallocFailed );
pNew = &standin;
}
if( pEList==0 ){
pEList = sqlite3ExprListAppend(pParse, 0,
sqlite3Expr(pParse->db,TK_ASTERISK,0));
}
pNew->pEList = pEList;
pNew->op = TK_SELECT;
pNew->selFlags = selFlags;
pNew->iLimit = 0;
pNew->iOffset = 0;
#if SELECTTRACE_ENABLED
pNew->zSelName[0] = 0;
#endif
pNew->addrOpenEphm[0] = -1;
pNew->addrOpenEphm[1] = -1;
pNew->nSelectRow = 0;
if( pSrc==0 ) pSrc = sqlite3DbMallocZero(pParse->db, sizeof(*pSrc));
pNew->pSrc = pSrc;
pNew->pWhere = pWhere;
pNew->pGroupBy = pGroupBy;
pNew->pHaving = pHaving;
pNew->pOrderBy = pOrderBy;
pNew->pPrior = 0;
pNew->pNext = 0;
pNew->pLimit = pLimit;
pNew->pWith = 0;
if( pParse->db->mallocFailed ) {
clearSelect(pParse->db, pNew, pNew!=&standin);
pNew = 0;
}else{
assert( pNew->pSrc!=0 || pParse->nErr>0 );
}
assert( pNew!=&standin );
return pNew;
}
#if SELECTTRACE_ENABLED
/*
** Set the name of a Select object
*/
void sqlite3SelectSetName(Select *p, const char *zName){
if( p && zName ){
sqlite3_snprintf(sizeof(p->zSelName), p->zSelName, "%s", zName);
}
}
#endif
/*
** Delete the given Select structure and all of its substructures.
*/
void sqlite3SelectDelete(sqlite3 *db, Select *p){
if( OK_IF_ALWAYS_TRUE(p) ) clearSelect(db, p, 1);
}
/*
** Return a pointer to the right-most SELECT statement in a compound.
*/
static Select *findRightmost(Select *p){
while( p->pNext ) p = p->pNext;
return p;
}
/*
** Given 1 to 3 identifiers preceding the JOIN keyword, determine the
** type of join. Return an integer constant that expresses that type
** in terms of the following bit values:
**
** JT_INNER
** JT_CROSS
** JT_OUTER
** JT_NATURAL
** JT_LEFT
** JT_RIGHT
**
** A full outer join is the combination of JT_LEFT and JT_RIGHT.
**
** If an illegal or unsupported join type is seen, then still return
** a join type, but put an error in the pParse structure.
*/
int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
int jointype = 0;
Token *apAll[3];
Token *p;
/* 0123456789 123456789 123456789 123 */
static const char zKeyText[] = "naturaleftouterightfullinnercross";
static const struct {
u8 i; /* Beginning of keyword text in zKeyText[] */
u8 nChar; /* Length of the keyword in characters */
u8 code; /* Join type mask */
} aKeyword[] = {
/* natural */ { 0, 7, JT_NATURAL },
/* left */ { 6, 4, JT_LEFT|JT_OUTER },
/* outer */ { 10, 5, JT_OUTER },
/* right */ { 14, 5, JT_RIGHT|JT_OUTER },
/* full */ { 19, 4, JT_LEFT|JT_RIGHT|JT_OUTER },
/* inner */ { 23, 5, JT_INNER },
/* cross */ { 28, 5, JT_INNER|JT_CROSS },
};
int i, j;
apAll[0] = pA;
apAll[1] = pB;
apAll[2] = pC;
for(i=0; i<3 && apAll[i]; i++){
p = apAll[i];
for(j=0; j<ArraySize(aKeyword); j++){
if( p->n==aKeyword[j].nChar
&& sqlite3StrNICmp((char*)p->z, &zKeyText[aKeyword[j].i], p->n)==0 ){
jointype |= aKeyword[j].code;
break;
}
}
testcase( j==0 || j==1 || j==2 || j==3 || j==4 || j==5 || j==6 );
if( j>=ArraySize(aKeyword) ){
jointype |= JT_ERROR;
break;
}
}
if(
(jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) ||
(jointype & JT_ERROR)!=0
){
const char *zSp = " ";
assert( pB!=0 );
if( pC==0 ){ zSp++; }
sqlite3ErrorMsg(pParse, "unknown or unsupported join type: "
"%T %T%s%T", pA, pB, zSp, pC);
jointype = JT_INNER;
}else if( (jointype & JT_OUTER)!=0
&& (jointype & (JT_LEFT|JT_RIGHT))!=JT_LEFT ){
sqlite3ErrorMsg(pParse,
"RIGHT and FULL OUTER JOINs are not currently supported");
jointype = JT_INNER;
}
return jointype;
}
/*
** Return the index of a column in a table. Return -1 if the column
** is not contained in the table.
*/
static int columnIndex(Table *pTab, const char *zCol){
int i;
for(i=0; i<pTab->nCol; i++){
if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i;
}
return -1;
}
/*
** Search the first N tables in pSrc, from left to right, looking for a
** table that has a column named zCol.
**
** When found, set *piTab and *piCol to the table index and column index
** of the matching column and return TRUE.
**
** If not found, return FALSE.
*/
static int tableAndColumnIndex(
SrcList *pSrc, /* Array of tables to search */
int N, /* Number of tables in pSrc->a[] to search */
const char *zCol, /* Name of the column we are looking for */
int *piTab, /* Write index of pSrc->a[] here */
int *piCol /* Write index of pSrc->a[*piTab].pTab->aCol[] here */
){
int i; /* For looping over tables in pSrc */
int iCol; /* Index of column matching zCol */
assert( (piTab==0)==(piCol==0) ); /* Both or neither are NULL */
for(i=0; i<N; i++){
iCol = columnIndex(pSrc->a[i].pTab, zCol);
if( iCol>=0 ){
if( piTab ){
*piTab = i;
*piCol = iCol;
}
return 1;
}
}
return 0;
}
/*
** This function is used to add terms implied by JOIN syntax to the
** WHERE clause expression of a SELECT statement. The new term, which
** is ANDed with the existing WHERE clause, is of the form:
**
** (tab1.col1 = tab2.col2)
**
** where tab1 is the iSrc'th table in SrcList pSrc and tab2 is the
** (iSrc+1)'th. Column col1 is column iColLeft of tab1, and col2 is
** column iColRight of tab2.
*/
static void addWhereTerm(
Parse *pParse, /* Parsing context */
SrcList *pSrc, /* List of tables in FROM clause */
int iLeft, /* Index of first table to join in pSrc */
int iColLeft, /* Index of column in first table */
int iRight, /* Index of second table in pSrc */
int iColRight, /* Index of column in second table */
int isOuterJoin, /* True if this is an OUTER join */
Expr **ppWhere /* IN/OUT: The WHERE clause to add to */
){
sqlite3 *db = pParse->db;
Expr *pE1;
Expr *pE2;
Expr *pEq;
assert( iLeft<iRight );
assert( pSrc->nSrc>iRight );
assert( pSrc->a[iLeft].pTab );
assert( pSrc->a[iRight].pTab );
pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iColLeft);
pE2 = sqlite3CreateColumnExpr(db, pSrc, iRight, iColRight);
pEq = sqlite3PExpr(pParse, TK_EQ, pE1, pE2);
if( pEq && isOuterJoin ){
ExprSetProperty(pEq, EP_FromJoin);
assert( !ExprHasProperty(pEq, EP_TokenOnly|EP_Reduced) );
ExprSetVVAProperty(pEq, EP_NoReduce);
pEq->iRightJoinTable = (i16)pE2->iTable;
}
*ppWhere = sqlite3ExprAnd(db, *ppWhere, pEq);
}
/*
** Set the EP_FromJoin property on all terms of the given expression.
** And set the Expr.iRightJoinTable to iTable for every term in the
** expression.
**
** The EP_FromJoin property is used on terms of an expression to tell
** the LEFT OUTER JOIN processing logic that this term is part of the
** join restriction specified in the ON or USING clause and not a part
** of the more general WHERE clause. These terms are moved over to the
** WHERE clause during join processing but we need to remember that they
** originated in the ON or USING clause.
**
** The Expr.iRightJoinTable tells the WHERE clause processing that the
** expression depends on table iRightJoinTable even if that table is not
** explicitly mentioned in the expression. That information is needed
** for cases like this:
**
** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5
**
** The where clause needs to defer the handling of the t1.x=5
** term until after the t2 loop of the join. In that way, a
** NULL t2 row will be inserted whenever t1.x!=5. If we do not
** defer the handling of t1.x=5, it will be processed immediately
** after the t1 loop and rows with t1.x!=5 will never appear in
** the output, which is incorrect.
*/
static void setJoinExpr(Expr *p, int iTable){
while( p ){
ExprSetProperty(p, EP_FromJoin);
assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
ExprSetVVAProperty(p, EP_NoReduce);
p->iRightJoinTable = (i16)iTable;
if( p->op==TK_FUNCTION && p->x.pList ){
int i;
for(i=0; i<p->x.pList->nExpr; i++){
setJoinExpr(p->x.pList->a[i].pExpr, iTable);
}
}
setJoinExpr(p->pLeft, iTable);
p = p->pRight;
}
}
/* Undo the work of setJoinExpr(). In the expression tree p, convert every
** term that is marked with EP_FromJoin and iRightJoinTable==iTable into
** an ordinary term that omits the EP_FromJoin mark.
**
** This happens when a LEFT JOIN is simplified into an ordinary JOIN.
*/
static void unsetJoinExpr(Expr *p, int iTable){
while( p ){
if( ExprHasProperty(p, EP_FromJoin)
&& (iTable<0 || p->iRightJoinTable==iTable) ){
ExprClearProperty(p, EP_FromJoin);
}
if( p->op==TK_FUNCTION && p->x.pList ){
int i;
for(i=0; i<p->x.pList->nExpr; i++){
unsetJoinExpr(p->x.pList->a[i].pExpr, iTable);
}
}
unsetJoinExpr(p->pLeft, iTable);
p = p->pRight;
}
}
/*
** This routine processes the join information for a SELECT statement.
** ON and USING clauses are converted into extra terms of the WHERE clause.
** NATURAL joins also create extra WHERE clause terms.
**
** The terms of a FROM clause are contained in the Select.pSrc structure.
** The left most table is the first entry in Select.pSrc. The right-most
** table is the last entry. The join operator is held in the entry to
** the left. Thus entry 0 contains the join operator for the join between
** entries 0 and 1. Any ON or USING clauses associated with the join are
** also attached to the left entry.
**
** This routine returns the number of errors encountered.
*/
static int sqliteProcessJoin(Parse *pParse, Select *p){
SrcList *pSrc; /* All tables in the FROM clause */
int i, j; /* Loop counters */
struct SrcList_item *pLeft; /* Left table being joined */
struct SrcList_item *pRight; /* Right table being joined */
pSrc = p->pSrc;
pLeft = &pSrc->a[0];
pRight = &pLeft[1];
for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){
Table *pRightTab = pRight->pTab;
int isOuter;
if( NEVER(pLeft->pTab==0 || pRightTab==0) ) continue;
isOuter = (pRight->fg.jointype & JT_OUTER)!=0;
/* When the NATURAL keyword is present, add WHERE clause terms for
** every column that the two tables have in common.
*/
if( pRight->fg.jointype & JT_NATURAL ){
if( pRight->pOn || pRight->pUsing ){
sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
"an ON or USING clause", 0);
return 1;
}
for(j=0; j<pRightTab->nCol; j++){
char *zName; /* Name of column in the right table */
int iLeft; /* Matching left table */
int iLeftCol; /* Matching column in the left table */
zName = pRightTab->aCol[j].zName;
if( tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) ){
addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j,
isOuter, &p->pWhere);
}
}
}
/* Disallow both ON and USING clauses in the same join
*/
if( pRight->pOn && pRight->pUsing ){
sqlite3ErrorMsg(pParse, "cannot have both ON and USING "
"clauses in the same join");
return 1;
}
/* Add the ON clause to the end of the WHERE clause, connected by
** an AND operator.
*/
if( pRight->pOn ){
if( isOuter ) setJoinExpr(pRight->pOn, pRight->iCursor);
p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn);
pRight->pOn = 0;
}
/* Create extra terms on the WHERE clause for each column named
** in the USING clause. Example: If the two tables to be joined are
** A and B and the USING clause names X, Y, and Z, then add this
** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z
** Report an error if any column mentioned in the USING clause is
** not contained in both tables to be joined.
*/
if( pRight->pUsing ){
IdList *pList = pRight->pUsing;
for(j=0; j<pList->nId; j++){
char *zName; /* Name of the term in the USING clause */
int iLeft; /* Table on the left with matching column name */
int iLeftCol; /* Column number of matching column on the left */
int iRightCol; /* Column number of matching column on the right */
zName = pList->a[j].zName;
iRightCol = columnIndex(pRightTab, zName);
if( iRightCol<0
|| !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol)
){
sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
"not present in both tables", zName);
return 1;
}
addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, iRightCol,
isOuter, &p->pWhere);
}
}
}
return 0;
}
/* Forward reference */
static KeyInfo *keyInfoFromExprList(
Parse *pParse, /* Parsing context */
ExprList *pList, /* Form the KeyInfo object from this ExprList */
int iStart, /* Begin with this column of pList */
int nExtra /* Add this many extra columns to the end */
);
/*
** An instance of this object holds information (beyond pParse and pSelect)
** needed to load the next result row that is to be added to the sorter.
*/
typedef struct RowLoadInfo RowLoadInfo;
struct RowLoadInfo {
int regResult; /* Store results in array of registers here */
u8 ecelFlags; /* Flag argument to ExprCodeExprList() */
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
ExprList *pExtra; /* Extra columns needed by sorter refs */
int regExtraResult; /* Where to load the extra columns */
#endif
};
/*
** This routine does the work of loading query data into an array of
** registers so that it can be added to the sorter.
*/
static void innerLoopLoadRow(
Parse *pParse, /* Statement under construction */
Select *pSelect, /* The query being coded */
RowLoadInfo *pInfo /* Info needed to complete the row load */
){
sqlite3ExprCodeExprList(pParse, pSelect->pEList, pInfo->regResult,
0, pInfo->ecelFlags);
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( pInfo->pExtra ){
sqlite3ExprCodeExprList(pParse, pInfo->pExtra, pInfo->regExtraResult, 0, 0);
sqlite3ExprListDelete(pParse->db, pInfo->pExtra);
}
#endif
}
/*
** Code the OP_MakeRecord instruction that generates the entry to be
** added into the sorter.
**
** Return the register in which the result is stored.
*/
static int makeSorterRecord(
Parse *pParse,
SortCtx *pSort,
Select *pSelect,
int regBase,
int nBase
){
int nOBSat = pSort->nOBSat;
Vdbe *v = pParse->pVdbe;
int regOut = ++pParse->nMem;
if( pSort->pDeferredRowLoad ){
innerLoopLoadRow(pParse, pSelect, pSort->pDeferredRowLoad);
}
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regOut);
return regOut;
}
/*
** Generate code that will push the record in registers regData
** through regData+nData-1 onto the sorter.
*/
static void pushOntoSorter(
Parse *pParse, /* Parser context */
SortCtx *pSort, /* Information about the ORDER BY clause */
Select *pSelect, /* The whole SELECT statement */
int regData, /* First register holding data to be sorted */
int regOrigData, /* First register holding data before packing */
int nData, /* Number of elements in the regData data array */
int nPrefixReg /* No. of reg prior to regData available for use */
){
Vdbe *v = pParse->pVdbe; /* Stmt under construction */
int bSeq = ((pSort->sortFlags & SORTFLAG_UseSorter)==0);
int nExpr = pSort->pOrderBy->nExpr; /* No. of ORDER BY terms */
int nBase = nExpr + bSeq + nData; /* Fields in sorter record */
int regBase; /* Regs for sorter record */
int regRecord = 0; /* Assembled sorter record */
int nOBSat = pSort->nOBSat; /* ORDER BY terms to skip */
int op; /* Opcode to add sorter record to sorter */
int iLimit; /* LIMIT counter */
int iSkip = 0; /* End of the sorter insert loop */
assert( bSeq==0 || bSeq==1 );
/* Three cases:
** (1) The data to be sorted has already been packed into a Record
** by a prior OP_MakeRecord. In this case nData==1 and regData
** will be completely unrelated to regOrigData.
** (2) All output columns are included in the sort record. In that
** case regData==regOrigData.
** (3) Some output columns are omitted from the sort record due to
** the SQLITE_ENABLE_SORTER_REFERENCE optimization, or due to the
** SQLITE_ECEL_OMITREF optimization. In that case, regOrigData==0
** to prevent this routine from trying to copy values that might
** not exist.
*/
assert( nData==1 || regData==regOrigData || regOrigData==0 );
if( nPrefixReg ){
assert( nPrefixReg==nExpr+bSeq );
regBase = regData - nPrefixReg;
}else{
regBase = pParse->nMem + 1;
pParse->nMem += nBase;
}
assert( pSelect->iOffset==0 || pSelect->iLimit!=0 );
iLimit = pSelect->iOffset ? pSelect->iOffset+1 : pSelect->iLimit;
pSort->labelDone = sqlite3VdbeMakeLabel(v);
sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData,
SQLITE_ECEL_DUP | (regOrigData? SQLITE_ECEL_REF : 0));
if( bSeq ){
sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr);
}
if( nPrefixReg==0 && nData>0 ){
sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+bSeq, nData);
}
if( nOBSat>0 ){
int regPrevKey; /* The first nOBSat columns of the previous row */
int addrFirst; /* Address of the OP_IfNot opcode */
int addrJmp; /* Address of the OP_Jump opcode */
VdbeOp *pOp; /* Opcode that opens the sorter */
int nKey; /* Number of sorting key columns, including OP_Sequence */
KeyInfo *pKI; /* Original KeyInfo on the sorter table */
regRecord = makeSorterRecord(pParse, pSort, pSelect, regBase, nBase);
regPrevKey = pParse->nMem+1;
pParse->nMem += pSort->nOBSat;
nKey = nExpr - pSort->nOBSat + bSeq;
if( bSeq ){
addrFirst = sqlite3VdbeAddOp1(v, OP_IfNot, regBase+nExpr);
}else{
addrFirst = sqlite3VdbeAddOp1(v, OP_SequenceTest, pSort->iECursor);
}
VdbeCoverage(v);
sqlite3VdbeAddOp3(v, OP_Compare, regPrevKey, regBase, pSort->nOBSat);
pOp = sqlite3VdbeGetOp(v, pSort->addrSortIndex);
if( pParse->db->mallocFailed ) return;
pOp->p2 = nKey + nData;
pKI = pOp->p4.pKeyInfo;
memset(pKI->aSortOrder, 0, pKI->nKeyField); /* Makes OP_Jump testable */
sqlite3VdbeChangeP4(v, -1, (char*)pKI, P4_KEYINFO);
testcase( pKI->nAllField > pKI->nKeyField+2 );
pOp->p4.pKeyInfo = keyInfoFromExprList(pParse, pSort->pOrderBy, nOBSat,
pKI->nAllField-pKI->nKeyField-1);
addrJmp = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp3(v, OP_Jump, addrJmp+1, 0, addrJmp+1); VdbeCoverage(v);
pSort->labelBkOut = sqlite3VdbeMakeLabel(v);
pSort->regReturn = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
sqlite3VdbeAddOp1(v, OP_ResetSorter, pSort->iECursor);
if( iLimit ){
sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, pSort->labelDone);
VdbeCoverage(v);
}
sqlite3VdbeJumpHere(v, addrFirst);
sqlite3ExprCodeMove(pParse, regBase, regPrevKey, pSort->nOBSat);
sqlite3VdbeJumpHere(v, addrJmp);
}
if( iLimit ){
/* At this point the values for the new sorter entry are stored
** in an array of registers. They need to be composed into a record
** and inserted into the sorter if either (a) there are currently
** less than LIMIT+OFFSET items or (b) the new record is smaller than
** the largest record currently in the sorter. If (b) is true and there
** are already LIMIT+OFFSET items in the sorter, delete the largest
** entry before inserting the new one. This way there are never more
** than LIMIT+OFFSET items in the sorter.
**
** If the new record does not need to be inserted into the sorter,
** jump to the next iteration of the loop. Or, if the
** pSort->bOrderedInnerLoop flag is set to indicate that the inner
** loop delivers items in sorted order, jump to the next iteration
** of the outer loop.
*/
int iCsr = pSort->iECursor;
sqlite3VdbeAddOp2(v, OP_IfNotZero, iLimit, sqlite3VdbeCurrentAddr(v)+4);
VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Last, iCsr, 0);
iSkip = sqlite3VdbeAddOp4Int(v, OP_IdxLE,
iCsr, 0, regBase+nOBSat, nExpr-nOBSat);
VdbeCoverage(v);
sqlite3VdbeAddOp1(v, OP_Delete, iCsr);
}
if( regRecord==0 ){
regRecord = makeSorterRecord(pParse, pSort, pSelect, regBase, nBase);
}
if( pSort->sortFlags & SORTFLAG_UseSorter ){
op = OP_SorterInsert;
}else{
op = OP_IdxInsert;
}
sqlite3VdbeAddOp4Int(v, op, pSort->iECursor, regRecord,
regBase+nOBSat, nBase-nOBSat);
if( iSkip ){
assert( pSort->bOrderedInnerLoop==0 || pSort->bOrderedInnerLoop==1 );
sqlite3VdbeChangeP2(v, iSkip,
sqlite3VdbeCurrentAddr(v) + pSort->bOrderedInnerLoop);
}
}
/*
** Add code to implement the OFFSET
*/
static void codeOffset(
Vdbe *v, /* Generate code into this VM */
int iOffset, /* Register holding the offset counter */
int iContinue /* Jump here to skip the current record */
){
if( iOffset>0 ){
sqlite3VdbeAddOp3(v, OP_IfPos, iOffset, iContinue, 1); VdbeCoverage(v);
VdbeComment((v, "OFFSET"));
}
}
/*
** Add code that will check to make sure the N registers starting at iMem
** form a distinct entry. iTab is a sorting index that holds previously
** seen combinations of the N values. A new entry is made in iTab
** if the current N values are new.
**
** A jump to addrRepeat is made and the N+1 values are popped from the
** stack if the top N elements are not distinct.
*/
static void codeDistinct(
Parse *pParse, /* Parsing and code generating context */
int iTab, /* A sorting index used to test for distinctness */
int addrRepeat, /* Jump to here if not distinct */
int N, /* Number of elements */
int iMem /* First element */
){
Vdbe *v;
int r1;
v = pParse->pVdbe;
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, iMem, N); VdbeCoverage(v);
sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iTab, r1, iMem, N);
sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
sqlite3ReleaseTempReg(pParse, r1);
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
/*
** This function is called as part of inner-loop generation for a SELECT
** statement with an ORDER BY that is not optimized by an index. It
** determines the expressions, if any, that the sorter-reference
** optimization should be used for. The sorter-reference optimization
** is used for SELECT queries like:
**
** SELECT a, bigblob FROM t1 ORDER BY a LIMIT 10
**
** If the optimization is used for expression "bigblob", then instead of
** storing values read from that column in the sorter records, the PK of
** the row from table t1 is stored instead. Then, as records are extracted from
** the sorter to return to the user, the required value of bigblob is
** retrieved directly from table t1. If the values are very large, this
** can be more efficient than storing them directly in the sorter records.
**
** The ExprList_item.bSorterRef flag is set for each expression in pEList
** for which the sorter-reference optimization should be enabled.
** Additionally, the pSort->aDefer[] array is populated with entries
** for all cursors required to evaluate all selected expressions. Finally.
** output variable (*ppExtra) is set to an expression list containing
** expressions for all extra PK values that should be stored in the
** sorter records.
*/
static void selectExprDefer(
Parse *pParse, /* Leave any error here */
SortCtx *pSort, /* Sorter context */
ExprList *pEList, /* Expressions destined for sorter */
ExprList **ppExtra /* Expressions to append to sorter record */
){
int i;
int nDefer = 0;
ExprList *pExtra = 0;
for(i=0; i<pEList->nExpr; i++){
struct ExprList_item *pItem = &pEList->a[i];
if( pItem->u.x.iOrderByCol==0 ){
Expr *pExpr = pItem->pExpr;
Table *pTab = pExpr->pTab;
if( pExpr->op==TK_COLUMN && pTab && !IsVirtual(pTab)
&& (pTab->aCol[pExpr->iColumn].colFlags & COLFLAG_SORTERREF)
){
int j;
for(j=0; j<nDefer; j++){
if( pSort->aDefer[j].iCsr==pExpr->iTable ) break;
}
if( j==nDefer ){
if( nDefer==ArraySize(pSort->aDefer) ){
continue;
}else{
int nKey = 1;
int k;
Index *pPk = 0;
if( !HasRowid(pTab) ){
pPk = sqlite3PrimaryKeyIndex(pTab);
nKey = pPk->nKeyCol;
}
for(k=0; k<nKey; k++){
Expr *pNew = sqlite3PExpr(pParse, TK_COLUMN, 0, 0);
if( pNew ){
pNew->iTable = pExpr->iTable;
pNew->pTab = pExpr->pTab;
pNew->iColumn = pPk ? pPk->aiColumn[k] : -1;
pExtra = sqlite3ExprListAppend(pParse, pExtra, pNew);
}
}
pSort->aDefer[nDefer].pTab = pExpr->pTab;
pSort->aDefer[nDefer].iCsr = pExpr->iTable;
pSort->aDefer[nDefer].nKey = nKey;
nDefer++;
}
}
pItem->bSorterRef = 1;
}
}
}
pSort->nDefer = (u8)nDefer;
*ppExtra = pExtra;
}
#endif
/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab is negative, then the p->pEList expressions
** are evaluated in order to get the data for this row. If srcTab is
** zero or more, then data is pulled from srcTab and p->pEList is used only
** to get the number of columns and the collation sequence for each column.
*/
static void selectInnerLoop(
Parse *pParse, /* The parser context */
Select *p, /* The complete select statement being coded */
int srcTab, /* Pull data from this table if non-negative */
SortCtx *pSort, /* If not NULL, info on how to process ORDER BY */
DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */
SelectDest *pDest, /* How to dispose of the results */
int iContinue, /* Jump here to continue with next row */
int iBreak /* Jump here to break out of the inner loop */
){
Vdbe *v = pParse->pVdbe;
int i;
int hasDistinct; /* True if the DISTINCT keyword is present */
int eDest = pDest->eDest; /* How to dispose of results */
int iParm = pDest->iSDParm; /* First argument to disposal method */
int nResultCol; /* Number of result columns */
int nPrefixReg = 0; /* Number of extra registers before regResult */
RowLoadInfo sRowLoadInfo; /* Info for deferred row loading */
/* Usually, regResult is the first cell in an array of memory cells
** containing the current result row. In this case regOrig is set to the
** same value. However, if the results are being sent to the sorter, the
** values for any expressions that are also part of the sort-key are omitted
** from this array. In this case regOrig is set to zero. */
int regResult; /* Start of memory holding current results */
int regOrig; /* Start of memory holding full result (or 0) */
assert( v );
assert( p->pEList!=0 );
hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
if( pSort && pSort->pOrderBy==0 ) pSort = 0;
if( pSort==0 && !hasDistinct ){
assert( iContinue!=0 );
codeOffset(v, p->iOffset, iContinue);
}
/* Pull the requested columns.
*/
nResultCol = p->pEList->nExpr;
if( pDest->iSdst==0 ){
if( pSort ){
nPrefixReg = pSort->pOrderBy->nExpr;
if( !(pSort->sortFlags & SORTFLAG_UseSorter) ) nPrefixReg++;
pParse->nMem += nPrefixReg;
}
pDest->iSdst = pParse->nMem+1;
pParse->nMem += nResultCol;
}else if( pDest->iSdst+nResultCol > pParse->nMem ){
/* This is an error condition that can result, for example, when a SELECT
** on the right-hand side of an INSERT contains more result columns than
** there are columns in the table on the left. The error will be caught
** and reported later. But we need to make sure enough memory is allocated
** to avoid other spurious errors in the meantime. */
pParse->nMem += nResultCol;
}
pDest->nSdst = nResultCol;
regOrig = regResult = pDest->iSdst;
if( srcTab>=0 ){
for(i=0; i<nResultCol; i++){
sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
VdbeComment((v, "%s", p->pEList->a[i].zName));
}
}else if( eDest!=SRT_Exists ){
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
ExprList *pExtra = 0;
#endif
/* If the destination is an EXISTS(...) expression, the actual
** values returned by the SELECT are not required.
*/
u8 ecelFlags; /* "ecel" is an abbreviation of "ExprCodeExprList" */
ExprList *pEList;
if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){
ecelFlags = SQLITE_ECEL_DUP;
}else{
ecelFlags = 0;
}
if( pSort && hasDistinct==0 && eDest!=SRT_EphemTab && eDest!=SRT_Table ){
/* For each expression in p->pEList that is a copy of an expression in
** the ORDER BY clause (pSort->pOrderBy), set the associated
** iOrderByCol value to one more than the index of the ORDER BY
** expression within the sort-key that pushOntoSorter() will generate.
** This allows the p->pEList field to be omitted from the sorted record,
** saving space and CPU cycles. */
ecelFlags |= (SQLITE_ECEL_OMITREF|SQLITE_ECEL_REF);
for(i=pSort->nOBSat; i<pSort->pOrderBy->nExpr; i++){
int j;
if( (j = pSort->pOrderBy->a[i].u.x.iOrderByCol)>0 ){
p->pEList->a[j-1].u.x.iOrderByCol = i+1-pSort->nOBSat;
}
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
selectExprDefer(pParse, pSort, p->pEList, &pExtra);
if( pExtra && pParse->db->mallocFailed==0 ){
/* If there are any extra PK columns to add to the sorter records,
** allocate extra memory cells and adjust the OpenEphemeral
** instruction to account for the larger records. This is only
** required if there are one or more WITHOUT ROWID tables with
** composite primary keys in the SortCtx.aDefer[] array. */
VdbeOp *pOp = sqlite3VdbeGetOp(v, pSort->addrSortIndex);
pOp->p2 += (pExtra->nExpr - pSort->nDefer);
pOp->p4.pKeyInfo->nAllField += (pExtra->nExpr - pSort->nDefer);
pParse->nMem += pExtra->nExpr;
}
#endif
/* Adjust nResultCol to account for columns that are omitted
** from the sorter by the optimizations in this branch */
pEList = p->pEList;
for(i=0; i<pEList->nExpr; i++){
if( pEList->a[i].u.x.iOrderByCol>0
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
|| pEList->a[i].bSorterRef
#endif
){
nResultCol--;
regOrig = 0;
}
}
testcase( regOrig );
testcase( eDest==SRT_Set );
testcase( eDest==SRT_Mem );
testcase( eDest==SRT_Coroutine );
testcase( eDest==SRT_Output );
assert( eDest==SRT_Set || eDest==SRT_Mem
|| eDest==SRT_Coroutine || eDest==SRT_Output );
}
sRowLoadInfo.regResult = regResult;
sRowLoadInfo.ecelFlags = ecelFlags;
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
sRowLoadInfo.pExtra = pExtra;
sRowLoadInfo.regExtraResult = regResult + nResultCol;
if( pExtra ) nResultCol += pExtra->nExpr;
#endif
if( p->iLimit
&& (ecelFlags & SQLITE_ECEL_OMITREF)!=0
&& nPrefixReg>0
){
assert( pSort!=0 );
assert( hasDistinct==0 );
pSort->pDeferredRowLoad = &sRowLoadInfo;
}else{
innerLoopLoadRow(pParse, p, &sRowLoadInfo);
}
}
/* If the DISTINCT keyword was present on the SELECT statement
** and this row has been seen before, then do not make this row
** part of the result.
*/
if( hasDistinct ){
switch( pDistinct->eTnctType ){
case WHERE_DISTINCT_ORDERED: {
VdbeOp *pOp; /* No longer required OpenEphemeral instr. */
int iJump; /* Jump destination */
int regPrev; /* Previous row content */
/* Allocate space for the previous row */
regPrev = pParse->nMem+1;
pParse->nMem += nResultCol;
/* Change the OP_OpenEphemeral coded earlier to an OP_Null
** sets the MEM_Cleared bit on the first register of the
** previous value. This will cause the OP_Ne below to always
** fail on the first iteration of the loop even if the first
** row is all NULLs.
*/
sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
pOp = sqlite3VdbeGetOp(v, pDistinct->addrTnct);
pOp->opcode = OP_Null;
pOp->p1 = 1;
pOp->p2 = regPrev;
iJump = sqlite3VdbeCurrentAddr(v) + nResultCol;
for(i=0; i<nResultCol; i++){
CollSeq *pColl = sqlite3ExprCollSeq(pParse, p->pEList->a[i].pExpr);
if( i<nResultCol-1 ){
sqlite3VdbeAddOp3(v, OP_Ne, regResult+i, iJump, regPrev+i);
VdbeCoverage(v);
}else{
sqlite3VdbeAddOp3(v, OP_Eq, regResult+i, iContinue, regPrev+i);
VdbeCoverage(v);
}
sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ);
sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
}
assert( sqlite3VdbeCurrentAddr(v)==iJump || pParse->db->mallocFailed );
sqlite3VdbeAddOp3(v, OP_Copy, regResult, regPrev, nResultCol-1);
break;
}
case WHERE_DISTINCT_UNIQUE: {
sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
break;
}
default: {
assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED );
codeDistinct(pParse, pDistinct->tabTnct, iContinue, nResultCol,
regResult);
break;
}
}
if( pSort==0 ){
codeOffset(v, p->iOffset, iContinue);
}
}
switch( eDest ){
/* In this mode, write each query result to the key of the temporary
** table iParm.
*/
#ifndef SQLITE_OMIT_COMPOUND_SELECT
case SRT_Union: {
int r1;
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, r1, regResult, nResultCol);
sqlite3ReleaseTempReg(pParse, r1);
break;
}
/* Construct a record from the query result, but instead of
** saving that record, use it as a key to delete elements from
** the temporary table iParm.
*/
case SRT_Except: {
sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nResultCol);
break;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */
/* Store the result as data using a unique key.
*/
case SRT_Fifo:
case SRT_DistFifo:
case SRT_Table:
case SRT_EphemTab: {
int r1 = sqlite3GetTempRange(pParse, nPrefixReg+1);
testcase( eDest==SRT_Table );
testcase( eDest==SRT_EphemTab );
testcase( eDest==SRT_Fifo );
testcase( eDest==SRT_DistFifo );
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1+nPrefixReg);
#ifndef SQLITE_OMIT_CTE
if( eDest==SRT_DistFifo ){
/* If the destination is DistFifo, then cursor (iParm+1) is open
** on an ephemeral index. If the current row is already present
** in the index, do not write it to the output. If not, add the
** current row to the index and proceed with writing it to the
** output table as well. */
int addr = sqlite3VdbeCurrentAddr(v) + 4;
sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0);
VdbeCoverage(v);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm+1, r1,regResult,nResultCol);
assert( pSort==0 );
}
#endif
if( pSort ){
assert( regResult==regOrig );
pushOntoSorter(pParse, pSort, p, r1+nPrefixReg, regOrig, 1, nPrefixReg);
}else{
int r2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2);
sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
sqlite3ReleaseTempReg(pParse, r2);
}
sqlite3ReleaseTempRange(pParse, r1, nPrefixReg+1);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
/* If we are creating a set for an "expr IN (SELECT ...)" construct,
** then there should be a single item on the stack. Write this
** item into the set table with bogus data.
*/
case SRT_Set: {
if( pSort ){
/* At first glance you would think we could optimize out the
** ORDER BY in this case since the order of entries in the set
** does not matter. But there might be a LIMIT clause, in which
** case the order does matter */
pushOntoSorter(
pParse, pSort, p, regResult, regOrig, nResultCol, nPrefixReg);
}else{
int r1 = sqlite3GetTempReg(pParse);
assert( sqlite3Strlen30(pDest->zAffSdst)==nResultCol );
sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, nResultCol,
r1, pDest->zAffSdst, nResultCol);
sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, r1, regResult, nResultCol);
sqlite3ReleaseTempReg(pParse, r1);
}
break;
}
/* If any row exist in the result set, record that fact and abort.
*/
case SRT_Exists: {
sqlite3VdbeAddOp2(v, OP_Integer, 1, iParm);
/* The LIMIT clause will terminate the loop for us */
break;
}
/* If this is a scalar select that is part of an expression, then
** store the results in the appropriate memory cell or array of
** memory cells and break out of the scan loop.
*/
case SRT_Mem: {
if( pSort ){
assert( nResultCol<=pDest->nSdst );
pushOntoSorter(
pParse, pSort, p, regResult, regOrig, nResultCol, nPrefixReg);
}else{
assert( nResultCol==pDest->nSdst );
assert( regResult==iParm );
/* The LIMIT clause will jump out of the loop for us */
}
break;
}
#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
case SRT_Coroutine: /* Send data to a co-routine */
case SRT_Output: { /* Return the results */
testcase( eDest==SRT_Coroutine );
testcase( eDest==SRT_Output );
if( pSort ){
pushOntoSorter(pParse, pSort, p, regResult, regOrig, nResultCol,
nPrefixReg);
}else if( eDest==SRT_Coroutine ){
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
}else{
sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nResultCol);
sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol);
}
break;
}
#ifndef SQLITE_OMIT_CTE
/* Write the results into a priority queue that is order according to
** pDest->pOrderBy (in pSO). pDest->iSDParm (in iParm) is the cursor for an
** index with pSO->nExpr+2 columns. Build a key using pSO for the first
** pSO->nExpr columns, then make sure all keys are unique by adding a
** final OP_Sequence column. The last column is the record as a blob.
*/
case SRT_DistQueue:
case SRT_Queue: {
int nKey;
int r1, r2, r3;
int addrTest = 0;
ExprList *pSO;
pSO = pDest->pOrderBy;
assert( pSO );
nKey = pSO->nExpr;
r1 = sqlite3GetTempReg(pParse);
r2 = sqlite3GetTempRange(pParse, nKey+2);
r3 = r2+nKey+1;
if( eDest==SRT_DistQueue ){
/* If the destination is DistQueue, then cursor (iParm+1) is open
** on a second ephemeral index that holds all values every previously
** added to the queue. */
addrTest = sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, 0,
regResult, nResultCol);
VdbeCoverage(v);
}
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r3);
if( eDest==SRT_DistQueue ){
sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r3);
sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
}
for(i=0; i<nKey; i++){
sqlite3VdbeAddOp2(v, OP_SCopy,
regResult + pSO->a[i].u.x.iOrderByCol - 1,
r2+i);
}
sqlite3VdbeAddOp2(v, OP_Sequence, iParm, r2+nKey);
sqlite3VdbeAddOp3(v, OP_MakeRecord, r2, nKey+2, r1);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, r1, r2, nKey+2);
if( addrTest ) sqlite3VdbeJumpHere(v, addrTest);
sqlite3ReleaseTempReg(pParse, r1);
sqlite3ReleaseTempRange(pParse, r2, nKey+2);
break;
}
#endif /* SQLITE_OMIT_CTE */
#if !defined(SQLITE_OMIT_TRIGGER)
/* Discard the results. This is used for SELECT statements inside
** the body of a TRIGGER. The purpose of such selects is to call
** user-defined functions that have side effects. We do not care
** about the actual results of the select.
*/
default: {
assert( eDest==SRT_Discard );
break;
}
#endif
}
/* Jump to the end of the loop if the LIMIT is reached. Except, if
** there is a sorter, in which case the sorter has already limited
** the output for us.
*/
if( pSort==0 && p->iLimit ){
sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v);
}
}
/*
** Allocate a KeyInfo object sufficient for an index of N key columns and
** X extra columns.
*/
KeyInfo *sqlite3KeyInfoAlloc(sqlite3 *db, int N, int X){
int nExtra = (N+X)*(sizeof(CollSeq*)+1) - sizeof(CollSeq*);
KeyInfo *p = sqlite3DbMallocRawNN(db, sizeof(KeyInfo) + nExtra);
if( p ){
p->aSortOrder = (u8*)&p->aColl[N+X];
p->nKeyField = (u16)N;
p->nAllField = (u16)(N+X);
p->enc = ENC(db);
p->db = db;
p->nRef = 1;
memset(&p[1], 0, nExtra);
}else{
sqlite3OomFault(db);
}
return p;
}
/*
** Deallocate a KeyInfo object
*/
void sqlite3KeyInfoUnref(KeyInfo *p){
if( p ){
assert( p->nRef>0 );
p->nRef--;
if( p->nRef==0 ) sqlite3DbFreeNN(p->db, p);
}
}
/*
** Make a new pointer to a KeyInfo object
*/
KeyInfo *sqlite3KeyInfoRef(KeyInfo *p){
if( p ){
assert( p->nRef>0 );
p->nRef++;
}
return p;
}
#ifdef SQLITE_DEBUG
/*
** Return TRUE if a KeyInfo object can be change. The KeyInfo object
** can only be changed if this is just a single reference to the object.
**
** This routine is used only inside of assert() statements.
*/
int sqlite3KeyInfoIsWriteable(KeyInfo *p){ return p->nRef==1; }
#endif /* SQLITE_DEBUG */
/*
** Given an expression list, generate a KeyInfo structure that records
** the collating sequence for each expression in that expression list.
**
** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
** KeyInfo structure is appropriate for initializing a virtual index to
** implement that clause. If the ExprList is the result set of a SELECT
** then the KeyInfo structure is appropriate for initializing a virtual
** index to implement a DISTINCT test.
**
** Space to hold the KeyInfo structure is obtained from malloc. The calling
** function is responsible for seeing that this structure is eventually
** freed.
*/
static KeyInfo *keyInfoFromExprList(
Parse *pParse, /* Parsing context */
ExprList *pList, /* Form the KeyInfo object from this ExprList */
int iStart, /* Begin with this column of pList */
int nExtra /* Add this many extra columns to the end */
){
int nExpr;
KeyInfo *pInfo;
struct ExprList_item *pItem;
sqlite3 *db = pParse->db;
int i;
nExpr = pList->nExpr;
pInfo = sqlite3KeyInfoAlloc(db, nExpr-iStart, nExtra+1);
if( pInfo ){
assert( sqlite3KeyInfoIsWriteable(pInfo) );
for(i=iStart, pItem=pList->a+iStart; i<nExpr; i++, pItem++){
pInfo->aColl[i-iStart] = sqlite3ExprNNCollSeq(pParse, pItem->pExpr);
pInfo->aSortOrder[i-iStart] = pItem->sortOrder;
}
}
return pInfo;
}
/*
** Name of the connection operator, used for error messages.
*/
static const char *selectOpName(int id){
char *z;
switch( id ){
case TK_ALL: z = "UNION ALL"; break;
case TK_INTERSECT: z = "INTERSECT"; break;
case TK_EXCEPT: z = "EXCEPT"; break;
default: z = "UNION"; break;
}
return z;
}
#ifndef SQLITE_OMIT_EXPLAIN
/*
** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
** is a no-op. Otherwise, it adds a single row of output to the EQP result,
** where the caption is of the form:
**
** "USE TEMP B-TREE FOR xxx"
**
** where xxx is one of "DISTINCT", "ORDER BY" or "GROUP BY". Exactly which
** is determined by the zUsage argument.
*/
static void explainTempTable(Parse *pParse, const char *zUsage){
ExplainQueryPlan((pParse, 0, "USE TEMP B-TREE FOR %s", zUsage));
}
/*
** Assign expression b to lvalue a. A second, no-op, version of this macro
** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code
** in sqlite3Select() to assign values to structure member variables that
** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the
** code with #ifndef directives.
*/
# define explainSetInteger(a, b) a = b
#else
/* No-op versions of the explainXXX() functions and macros. */
# define explainTempTable(y,z)
# define explainSetInteger(y,z)
#endif
/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter. After the loop is terminated
** we need to run the sorter and output the results. The following
** routine generates the code needed to do that.
*/
static void generateSortTail(
Parse *pParse, /* Parsing context */
Select *p, /* The SELECT statement */
SortCtx *pSort, /* Information on the ORDER BY clause */
int nColumn, /* Number of columns of data */
SelectDest *pDest /* Write the sorted results here */
){
Vdbe *v = pParse->pVdbe; /* The prepared statement */
int addrBreak = pSort->labelDone; /* Jump here to exit loop */
int addrContinue = sqlite3VdbeMakeLabel(v); /* Jump here for next cycle */
int addr; /* Top of output loop. Jump for Next. */
int addrOnce = 0;
int iTab;
ExprList *pOrderBy = pSort->pOrderBy;
int eDest = pDest->eDest;
int iParm = pDest->iSDParm;
int regRow;
int regRowid;
int iCol;
int nKey; /* Number of key columns in sorter record */
int iSortTab; /* Sorter cursor to read from */
int i;
int bSeq; /* True if sorter record includes seq. no. */
int nRefKey = 0;
struct ExprList_item *aOutEx = p->pEList->a;
assert( addrBreak<0 );
if( pSort->labelBkOut ){
sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
sqlite3VdbeGoto(v, addrBreak);
sqlite3VdbeResolveLabel(v, pSort->labelBkOut);
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
/* Open any cursors needed for sorter-reference expressions */
for(i=0; i<pSort->nDefer; i++){
Table *pTab = pSort->aDefer[i].pTab;
int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
sqlite3OpenTable(pParse, pSort->aDefer[i].iCsr, iDb, pTab, OP_OpenRead);
nRefKey = MAX(nRefKey, pSort->aDefer[i].nKey);
}
#endif
iTab = pSort->iECursor;
if( eDest==SRT_Output || eDest==SRT_Coroutine || eDest==SRT_Mem ){
regRowid = 0;
regRow = pDest->iSdst;
}else{
regRowid = sqlite3GetTempReg(pParse);
regRow = sqlite3GetTempRange(pParse, nColumn);
}
nKey = pOrderBy->nExpr - pSort->nOBSat;
if( pSort->sortFlags & SORTFLAG_UseSorter ){
int regSortOut = ++pParse->nMem;
iSortTab = pParse->nTab++;
if( pSort->labelBkOut ){
addrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
}
sqlite3VdbeAddOp3(v, OP_OpenPseudo, iSortTab, regSortOut,
nKey+1+nColumn+nRefKey);
if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce);
addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
VdbeCoverage(v);
codeOffset(v, p->iOffset, addrContinue);
sqlite3VdbeAddOp3(v, OP_SorterData, iTab, regSortOut, iSortTab);
bSeq = 0;
}else{
addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak); VdbeCoverage(v);
codeOffset(v, p->iOffset, addrContinue);
iSortTab = iTab;
bSeq = 1;
}
for(i=0, iCol=nKey+bSeq-1; i<nColumn; i++){
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( aOutEx[i].bSorterRef ) continue;
#endif
if( aOutEx[i].u.x.iOrderByCol==0 ) iCol++;
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( pSort->nDefer ){
int iKey = iCol+1;
int regKey = sqlite3GetTempRange(pParse, nRefKey);
for(i=0; i<pSort->nDefer; i++){
int iCsr = pSort->aDefer[i].iCsr;
Table *pTab = pSort->aDefer[i].pTab;
int nKey = pSort->aDefer[i].nKey;
sqlite3VdbeAddOp1(v, OP_NullRow, iCsr);
if( HasRowid(pTab) ){
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, iKey++, regKey);
sqlite3VdbeAddOp3(v, OP_SeekRowid, iCsr,
sqlite3VdbeCurrentAddr(v)+1, regKey);
}else{
int k;
int iJmp;
assert( sqlite3PrimaryKeyIndex(pTab)->nKeyCol==nKey );
for(k=0; k<nKey; k++){
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, iKey++, regKey+k);
}
iJmp = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp4Int(v, OP_SeekGE, iCsr, iJmp+2, regKey, nKey);
sqlite3VdbeAddOp4Int(v, OP_IdxLE, iCsr, iJmp+3, regKey, nKey);
sqlite3VdbeAddOp1(v, OP_NullRow, iCsr);
}
}
sqlite3ReleaseTempRange(pParse, regKey, nRefKey);
}
#endif
for(i=nColumn-1; i>=0; i--){
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( aOutEx[i].bSorterRef ){
sqlite3ExprCode(pParse, aOutEx[i].pExpr, regRow+i);
}else
#endif
{
int iRead;
if( aOutEx[i].u.x.iOrderByCol ){
iRead = aOutEx[i].u.x.iOrderByCol-1;
}else{
iRead = iCol--;
}
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, iRead, regRow+i);
VdbeComment((v, "%s", aOutEx[i].zName?aOutEx[i].zName : aOutEx[i].zSpan));
}
}
switch( eDest ){
case SRT_Table:
case SRT_EphemTab: {
sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iParm, regRow, regRowid);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
case SRT_Set: {
assert( nColumn==sqlite3Strlen30(pDest->zAffSdst) );
sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, nColumn, regRowid,
pDest->zAffSdst, nColumn);
sqlite3ExprCacheAffinityChange(pParse, regRow, nColumn);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, regRowid, regRow, nColumn);
break;
}
case SRT_Mem: {
/* The LIMIT clause will terminate the loop for us */
break;
}
#endif
default: {
assert( eDest==SRT_Output || eDest==SRT_Coroutine );
testcase( eDest==SRT_Output );
testcase( eDest==SRT_Coroutine );
if( eDest==SRT_Output ){
sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iSdst, nColumn);
sqlite3ExprCacheAffinityChange(pParse, pDest->iSdst, nColumn);
}else{
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
}
break;
}
}
if( regRowid ){
if( eDest==SRT_Set ){
sqlite3ReleaseTempRange(pParse, regRow, nColumn);
}else{
sqlite3ReleaseTempReg(pParse, regRow);
}
sqlite3ReleaseTempReg(pParse, regRowid);
}
/* The bottom of the loop
*/
sqlite3VdbeResolveLabel(v, addrContinue);
if( pSort->sortFlags & SORTFLAG_UseSorter ){
sqlite3VdbeAddOp2(v, OP_SorterNext, iTab, addr); VdbeCoverage(v);
}else{
sqlite3VdbeAddOp2(v, OP_Next, iTab, addr); VdbeCoverage(v);
}
if( pSort->regReturn ) sqlite3VdbeAddOp1(v, OP_Return, pSort->regReturn);
sqlite3VdbeResolveLabel(v, addrBreak);
}
/*
** Return a pointer to a string containing the 'declaration type' of the
** expression pExpr. The string may be treated as static by the caller.
**
** Also try to estimate the size of the returned value and return that
** result in *pEstWidth.
**
** The declaration type is the exact datatype definition extracted from the
** original CREATE TABLE statement if the expression is a column. The
** declaration type for a ROWID field is INTEGER. Exactly when an expression
** is considered a column can be complex in the presence of subqueries. The
** result-set expression in all of the following SELECT statements is
** considered a column by this function.
**
** SELECT col FROM tbl;
** SELECT (SELECT col FROM tbl;
** SELECT (SELECT col FROM tbl);
** SELECT abc FROM (SELECT col AS abc FROM tbl);
**
** The declaration type for any expression other than a column is NULL.
**
** This routine has either 3 or 6 parameters depending on whether or not
** the SQLITE_ENABLE_COLUMN_METADATA compile-time option is used.
*/
#ifdef SQLITE_ENABLE_COLUMN_METADATA
# define columnType(A,B,C,D,E) columnTypeImpl(A,B,C,D,E)
#else /* if !defined(SQLITE_ENABLE_COLUMN_METADATA) */
# define columnType(A,B,C,D,E) columnTypeImpl(A,B)
#endif
static const char *columnTypeImpl(
NameContext *pNC,
#ifndef SQLITE_ENABLE_COLUMN_METADATA
Expr *pExpr
#else
Expr *pExpr,
const char **pzOrigDb,
const char **pzOrigTab,
const char **pzOrigCol
#endif
){
char const *zType = 0;
int j;
#ifdef SQLITE_ENABLE_COLUMN_METADATA
char const *zOrigDb = 0;
char const *zOrigTab = 0;
char const *zOrigCol = 0;
#endif
assert( pExpr!=0 );
assert( pNC->pSrcList!=0 );
assert( pExpr->op!=TK_AGG_COLUMN ); /* This routine runes before aggregates
** are processed */
switch( pExpr->op ){
case TK_COLUMN: {
/* The expression is a column. Locate the table the column is being
** extracted from in NameContext.pSrcList. This table may be real
** database table or a subquery.
*/
Table *pTab = 0; /* Table structure column is extracted from */
Select *pS = 0; /* Select the column is extracted from */
int iCol = pExpr->iColumn; /* Index of column in pTab */
while( pNC && !pTab ){
SrcList *pTabList = pNC->pSrcList;
for(j=0;j<pTabList->nSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++);
if( j<pTabList->nSrc ){
pTab = pTabList->a[j].pTab;
pS = pTabList->a[j].pSelect;
}else{
pNC = pNC->pNext;
}
}
if( pTab==0 ){
/* At one time, code such as "SELECT new.x" within a trigger would
** cause this condition to run. Since then, we have restructured how
** trigger code is generated and so this condition is no longer
** possible. However, it can still be true for statements like
** the following:
**
** CREATE TABLE t1(col INTEGER);
** SELECT (SELECT t1.col) FROM FROM t1;
**
** when columnType() is called on the expression "t1.col" in the
** sub-select. In this case, set the column type to NULL, even
** though it should really be "INTEGER".
**
** This is not a problem, as the column type of "t1.col" is never
** used. When columnType() is called on the expression
** "(SELECT t1.col)", the correct type is returned (see the TK_SELECT
** branch below. */
break;
}
assert( pTab && pExpr->pTab==pTab );
if( pS ){
/* The "table" is actually a sub-select or a view in the FROM clause
** of the SELECT statement. Return the declaration type and origin
** data for the result-set column of the sub-select.
*/
if( iCol>=0 && iCol<pS->pEList->nExpr ){
/* If iCol is less than zero, then the expression requests the
** rowid of the sub-select or view. This expression is legal (see
** test case misc2.2.2) - it always evaluates to NULL.
*/
NameContext sNC;
Expr *p = pS->pEList->a[iCol].pExpr;
sNC.pSrcList = pS->pSrc;
sNC.pNext = pNC;
sNC.pParse = pNC->pParse;
zType = columnType(&sNC, p,&zOrigDb,&zOrigTab,&zOrigCol);
}
}else{
/* A real table or a CTE table */
assert( !pS );
#ifdef SQLITE_ENABLE_COLUMN_METADATA
if( iCol<0 ) iCol = pTab->iPKey;
assert( iCol==XN_ROWID || (iCol>=0 && iCol<pTab->nCol) );
if( iCol<0 ){
zType = "INTEGER";
zOrigCol = "rowid";
}else{
zOrigCol = pTab->aCol[iCol].zName;
zType = sqlite3ColumnType(&pTab->aCol[iCol],0);
}
zOrigTab = pTab->zName;
if( pNC->pParse && pTab->pSchema ){
int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema);
zOrigDb = pNC->pParse->db->aDb[iDb].zDbSName;
}
#else
assert( iCol==XN_ROWID || (iCol>=0 && iCol<pTab->nCol) );
if( iCol<0 ){
zType = "INTEGER";
}else{
zType = sqlite3ColumnType(&pTab->aCol[iCol],0);
}
#endif
}
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
case TK_SELECT: {
/* The expression is a sub-select. Return the declaration type and
** origin info for the single column in the result set of the SELECT
** statement.
*/
NameContext sNC;
Select *pS = pExpr->x.pSelect;
Expr *p = pS->pEList->a[0].pExpr;
assert( ExprHasProperty(pExpr, EP_xIsSelect) );
sNC.pSrcList = pS->pSrc;
sNC.pNext = pNC;
sNC.pParse = pNC->pParse;
zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
break;
}
#endif
}
#ifdef SQLITE_ENABLE_COLUMN_METADATA
if( pzOrigDb ){
assert( pzOrigTab && pzOrigCol );
*pzOrigDb = zOrigDb;
*pzOrigTab = zOrigTab;
*pzOrigCol = zOrigCol;
}
#endif
return zType;
}
/*
** Generate code that will tell the VDBE the declaration types of columns
** in the result set.
*/
static void generateColumnTypes(
Parse *pParse, /* Parser context */
SrcList *pTabList, /* List of tables */
ExprList *pEList /* Expressions defining the result set */
){
#ifndef SQLITE_OMIT_DECLTYPE
Vdbe *v = pParse->pVdbe;
int i;
NameContext sNC;
sNC.pSrcList = pTabList;
sNC.pParse = pParse;
sNC.pNext = 0;
for(i=0; i<pEList->nExpr; i++){
Expr *p = pEList->a[i].pExpr;
const char *zType;
#ifdef SQLITE_ENABLE_COLUMN_METADATA
const char *zOrigDb = 0;
const char *zOrigTab = 0;
const char *zOrigCol = 0;
zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
/* The vdbe must make its own copy of the column-type and other
** column specific strings, in case the schema is reset before this
** virtual machine is deleted.
*/
sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, SQLITE_TRANSIENT);
sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, SQLITE_TRANSIENT);
sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, SQLITE_TRANSIENT);
#else
zType = columnType(&sNC, p, 0, 0, 0);
#endif
sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, SQLITE_TRANSIENT);
}
#endif /* !defined(SQLITE_OMIT_DECLTYPE) */
}
/*
** Compute the column names for a SELECT statement.
**
** The only guarantee that SQLite makes about column names is that if the
** column has an AS clause assigning it a name, that will be the name used.
** That is the only documented guarantee. However, countless applications
** developed over the years have made baseless assumptions about column names
** and will break if those assumptions changes. Hence, use extreme caution
** when modifying this routine to avoid breaking legacy.
**
** See Also: sqlite3ColumnsFromExprList()
**
** The PRAGMA short_column_names and PRAGMA full_column_names settings are
** deprecated. The default setting is short=ON, full=OFF. 99.9% of all
** applications should operate this way. Nevertheless, we need to support the
** other modes for legacy:
**
** short=OFF, full=OFF: Column name is the text of the expression has it
** originally appears in the SELECT statement. In
** other words, the zSpan of the result expression.
**
** short=ON, full=OFF: (This is the default setting). If the result
** refers directly to a table column, then the
** result column name is just the table column
** name: COLUMN. Otherwise use zSpan.
**
** full=ON, short=ANY: If the result refers directly to a table column,
** then the result column name with the table name
** prefix, ex: TABLE.COLUMN. Otherwise use zSpan.
*/
static void generateColumnNames(
Parse *pParse, /* Parser context */
Select *pSelect /* Generate column names for this SELECT statement */
){
Vdbe *v = pParse->pVdbe;
int i;
Table *pTab;
SrcList *pTabList;
ExprList *pEList;
sqlite3 *db = pParse->db;
int fullName; /* TABLE.COLUMN if no AS clause and is a direct table ref */
int srcName; /* COLUMN or TABLE.COLUMN if no AS clause and is direct */
#ifndef SQLITE_OMIT_EXPLAIN
/* If this is an EXPLAIN, skip this step */
if( pParse->explain ){
return;
}
#endif
if( pParse->colNamesSet ) return;
/* Column names are determined by the left-most term of a compound select */
while( pSelect->pPrior ) pSelect = pSelect->pPrior;
SELECTTRACE(1,pParse,pSelect,("generating column names\n"));
pTabList = pSelect->pSrc;
pEList = pSelect->pEList;
assert( v!=0 );
assert( pTabList!=0 );
pParse->colNamesSet = 1;
fullName = (db->flags & SQLITE_FullColNames)!=0;
srcName = (db->flags & SQLITE_ShortColNames)!=0 || fullName;
sqlite3VdbeSetNumCols(v, pEList->nExpr);
for(i=0; i<pEList->nExpr; i++){
Expr *p = pEList->a[i].pExpr;
assert( p!=0 );
assert( p->op!=TK_AGG_COLUMN ); /* Agg processing has not run yet */
assert( p->op!=TK_COLUMN || p->pTab!=0 ); /* Covering idx not yet coded */
if( pEList->a[i].zName ){
/* An AS clause always takes first priority */
char *zName = pEList->a[i].zName;
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT);
}else if( srcName && p->op==TK_COLUMN ){
char *zCol;
int iCol = p->iColumn;
pTab = p->pTab;
assert( pTab!=0 );
if( iCol<0 ) iCol = pTab->iPKey;
assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
if( iCol<0 ){
zCol = "rowid";
}else{
zCol = pTab->aCol[iCol].zName;
}
if( fullName ){
char *zName = 0;
zName = sqlite3MPrintf(db, "%s.%s", pTab->zName, zCol);
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_DYNAMIC);
}else{
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, SQLITE_TRANSIENT);
}
}else{
const char *z = pEList->a[i].zSpan;
z = z==0 ? sqlite3MPrintf(db, "column%d", i+1) : sqlite3DbStrDup(db, z);
sqlite3VdbeSetColName(v, i, COLNAME_NAME, z, SQLITE_DYNAMIC);
}
}
generateColumnTypes(pParse, pTabList, pEList);
}
/*
** Given an expression list (which is really the list of expressions
** that form the result set of a SELECT statement) compute appropriate
** column names for a table that would hold the expression list.
**
** All column names will be unique.
**
** Only the column names are computed. Column.zType, Column.zColl,
** and other fields of Column are zeroed.
**
** Return SQLITE_OK on success. If a memory allocation error occurs,
** store NULL in *paCol and 0 in *pnCol and return SQLITE_NOMEM.
**
** The only guarantee that SQLite makes about column names is that if the
** column has an AS clause assigning it a name, that will be the name used.
** That is the only documented guarantee. However, countless applications
** developed over the years have made baseless assumptions about column names
** and will break if those assumptions changes. Hence, use extreme caution
** when modifying this routine to avoid breaking legacy.
**
** See Also: generateColumnNames()
*/
int sqlite3ColumnsFromExprList(
Parse *pParse, /* Parsing context */
ExprList *pEList, /* Expr list from which to derive column names */
i16 *pnCol, /* Write the number of columns here */
Column **paCol /* Write the new column list here */
){
sqlite3 *db = pParse->db; /* Database connection */
int i, j; /* Loop counters */
u32 cnt; /* Index added to make the name unique */
Column *aCol, *pCol; /* For looping over result columns */
int nCol; /* Number of columns in the result set */
char *zName; /* Column name */
int nName; /* Size of name in zName[] */
Hash ht; /* Hash table of column names */
sqlite3HashInit(&ht);
if( pEList ){
nCol = pEList->nExpr;
aCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol);
testcase( aCol==0 );
if( nCol>32767 ) nCol = 32767;
}else{
nCol = 0;
aCol = 0;
}
assert( nCol==(i16)nCol );
*pnCol = nCol;
*paCol = aCol;
for(i=0, pCol=aCol; i<nCol && !db->mallocFailed; i++, pCol++){
/* Get an appropriate name for the column
*/
if( (zName = pEList->a[i].zName)!=0 ){
/* If the column contains an "AS <name>" phrase, use <name> as the name */
}else{
Expr *pColExpr = sqlite3ExprSkipCollate(pEList->a[i].pExpr);
while( pColExpr->op==TK_DOT ){
pColExpr = pColExpr->pRight;
assert( pColExpr!=0 );
}
assert( pColExpr->op!=TK_AGG_COLUMN );
if( pColExpr->op==TK_COLUMN ){
/* For columns use the column name name */
int iCol = pColExpr->iColumn;
Table *pTab = pColExpr->pTab;
assert( pTab!=0 );
if( iCol<0 ) iCol = pTab->iPKey;
zName = iCol>=0 ? pTab->aCol[iCol].zName : "rowid";
}else if( pColExpr->op==TK_ID ){
assert( !ExprHasProperty(pColExpr, EP_IntValue) );
zName = pColExpr->u.zToken;
}else{
/* Use the original text of the column expression as its name */
zName = pEList->a[i].zSpan;
}
}
if( zName ){
zName = sqlite3DbStrDup(db, zName);
}else{
zName = sqlite3MPrintf(db,"column%d",i+1);
}
/* Make sure the column name is unique. If the name is not unique,
** append an integer to the name so that it becomes unique.
*/
cnt = 0;
while( zName && sqlite3HashFind(&ht, zName)!=0 ){
nName = sqlite3Strlen30(zName);
if( nName>0 ){
for(j=nName-1; j>0 && sqlite3Isdigit(zName[j]); j--){}
if( zName[j]==':' ) nName = j;
}
zName = sqlite3MPrintf(db, "%.*z:%u", nName, zName, ++cnt);
if( cnt>3 ) sqlite3_randomness(sizeof(cnt), &cnt);
}
pCol->zName = zName;
sqlite3ColumnPropertiesFromName(0, pCol);
if( zName && sqlite3HashInsert(&ht, zName, pCol)==pCol ){
sqlite3OomFault(db);
}
}
sqlite3HashClear(&ht);
if( db->mallocFailed ){
for(j=0; j<i; j++){
sqlite3DbFree(db, aCol[j].zName);
}
sqlite3DbFree(db, aCol);
*paCol = 0;
*pnCol = 0;
return SQLITE_NOMEM_BKPT;
}
return SQLITE_OK;
}
/*
** Add type and collation information to a column list based on
** a SELECT statement.
**
** The column list presumably came from selectColumnNamesFromExprList().
** The column list has only names, not types or collations. This
** routine goes through and adds the types and collations.
**
** This routine requires that all identifiers in the SELECT
** statement be resolved.
*/
void sqlite3SelectAddColumnTypeAndCollation(
Parse *pParse, /* Parsing contexts */
Table *pTab, /* Add column type information to this table */
Select *pSelect /* SELECT used to determine types and collations */
){
sqlite3 *db = pParse->db;
NameContext sNC;
Column *pCol;
CollSeq *pColl;
int i;
Expr *p;
struct ExprList_item *a;
assert( pSelect!=0 );
assert( (pSelect->selFlags & SF_Resolved)!=0 );
assert( pTab->nCol==pSelect->pEList->nExpr || db->mallocFailed );
if( db->mallocFailed ) return;
memset(&sNC, 0, sizeof(sNC));
sNC.pSrcList = pSelect->pSrc;
a = pSelect->pEList->a;
for(i=0, pCol=pTab->aCol; i<pTab->nCol; i++, pCol++){
const char *zType;
int n, m;
p = a[i].pExpr;
zType = columnType(&sNC, p, 0, 0, 0);
/* pCol->szEst = ... // Column size est for SELECT tables never used */
pCol->affinity = sqlite3ExprAffinity(p);
if( zType ){
m = sqlite3Strlen30(zType);
n = sqlite3Strlen30(pCol->zName);
pCol->zName = sqlite3DbReallocOrFree(db, pCol->zName, n+m+2);
if( pCol->zName ){
memcpy(&pCol->zName[n+1], zType, m+1);
pCol->colFlags |= COLFLAG_HASTYPE;
}
}
if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_BLOB;
pColl = sqlite3ExprCollSeq(pParse, p);
if( pColl && pCol->zColl==0 ){
pCol->zColl = sqlite3DbStrDup(db, pColl->zName);
}
}
pTab->szTabRow = 1; /* Any non-zero value works */
}
/*
** Given a SELECT statement, generate a Table structure that describes
** the result set of that SELECT.
*/
Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect){
Table *pTab;
sqlite3 *db = pParse->db;
int savedFlags;
savedFlags = db->flags;
db->flags &= ~SQLITE_FullColNames;
db->flags |= SQLITE_ShortColNames;
sqlite3SelectPrep(pParse, pSelect, 0);
if( pParse->nErr ) return 0;
while( pSelect->pPrior ) pSelect = pSelect->pPrior;
db->flags = savedFlags;
pTab = sqlite3DbMallocZero(db, sizeof(Table) );
if( pTab==0 ){
return 0;
}
/* The sqlite3ResultSetOfSelect() is only used n contexts where lookaside
** is disabled */
assert( db->lookaside.bDisable );
pTab->nTabRef = 1;
pTab->zName = 0;
pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
sqlite3ColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol);
sqlite3SelectAddColumnTypeAndCollation(pParse, pTab, pSelect);
pTab->iPKey = -1;
if( db->mallocFailed ){
sqlite3DeleteTable(db, pTab);
return 0;
}
return pTab;
}
/*
** Get a VDBE for the given parser context. Create a new one if necessary.
** If an error occurs, return NULL and leave a message in pParse.
*/
Vdbe *sqlite3GetVdbe(Parse *pParse){
if( pParse->pVdbe ){
return pParse->pVdbe;
}
if( pParse->pToplevel==0
&& OptimizationEnabled(pParse->db,SQLITE_FactorOutConst)
){
pParse->okConstFactor = 1;
}
return sqlite3VdbeCreate(pParse);
}
/*
** Compute the iLimit and iOffset fields of the SELECT based on the
** pLimit expressions. pLimit->pLeft and pLimit->pRight hold the expressions
** that appear in the original SQL statement after the LIMIT and OFFSET
** keywords. Or NULL if those keywords are omitted. iLimit and iOffset
** are the integer memory register numbers for counters used to compute
** the limit and offset. If there is no limit and/or offset, then
** iLimit and iOffset are negative.
**
** This routine changes the values of iLimit and iOffset only if
** a limit or offset is defined by pLimit->pLeft and pLimit->pRight. iLimit
** and iOffset should have been preset to appropriate default values (zero)
** prior to calling this routine.
**
** The iOffset register (if it exists) is initialized to the value
** of the OFFSET. The iLimit register is initialized to LIMIT. Register
** iOffset+1 is initialized to LIMIT+OFFSET.
**
** Only if pLimit->pLeft!=0 do the limit registers get
** redefined. The UNION ALL operator uses this property to force
** the reuse of the same limit and offset registers across multiple
** SELECT statements.
*/
static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
Vdbe *v = 0;
int iLimit = 0;
int iOffset;
int n;
Expr *pLimit = p->pLimit;
if( p->iLimit ) return;
/*
** "LIMIT -1" always shows all rows. There is some
** controversy about what the correct behavior should be.
** The current implementation interprets "LIMIT 0" to mean
** no rows.
*/
sqlite3ExprCacheClear(pParse);
if( pLimit ){
assert( pLimit->op==TK_LIMIT );
assert( pLimit->pLeft!=0 );
p->iLimit = iLimit = ++pParse->nMem;
v = sqlite3GetVdbe(pParse);
assert( v!=0 );
if( sqlite3ExprIsInteger(pLimit->pLeft, &n) ){
sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit);
VdbeComment((v, "LIMIT counter"));
if( n==0 ){
sqlite3VdbeGoto(v, iBreak);
}else if( n>=0 && p->nSelectRow>sqlite3LogEst((u64)n) ){
p->nSelectRow = sqlite3LogEst((u64)n);
p->selFlags |= SF_FixedLimit;
}
}else{
sqlite3ExprCode(pParse, pLimit->pLeft, iLimit);
sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit); VdbeCoverage(v);
VdbeComment((v, "LIMIT counter"));
sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, iBreak); VdbeCoverage(v);
}
if( pLimit->pRight ){
p->iOffset = iOffset = ++pParse->nMem;
pParse->nMem++; /* Allocate an extra register for limit+offset */
sqlite3ExprCode(pParse, pLimit->pRight, iOffset);
sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset); VdbeCoverage(v);
VdbeComment((v, "OFFSET counter"));
sqlite3VdbeAddOp3(v, OP_OffsetLimit, iLimit, iOffset+1, iOffset);
VdbeComment((v, "LIMIT+OFFSET"));
}
}
}
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** Return the appropriate collating sequence for the iCol-th column of
** the result set for the compound-select statement "p". Return NULL if
** the column has no default collating sequence.
**
** The collating sequence for the compound select is taken from the
** left-most term of the select that has a collating sequence.
*/
static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){
CollSeq *pRet;
if( p->pPrior ){
pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
}else{
pRet = 0;
}
assert( iCol>=0 );
/* iCol must be less than p->pEList->nExpr. Otherwise an error would
** have been thrown during name resolution and we would not have gotten
** this far */
if( pRet==0 && ALWAYS(iCol<p->pEList->nExpr) ){
pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
}
return pRet;
}
/*
** The select statement passed as the second parameter is a compound SELECT
** with an ORDER BY clause. This function allocates and returns a KeyInfo
** structure suitable for implementing the ORDER BY.
**
** Space to hold the KeyInfo structure is obtained from malloc. The calling
** function is responsible for ensuring that this structure is eventually
** freed.
*/
static KeyInfo *multiSelectOrderByKeyInfo(Parse *pParse, Select *p, int nExtra){
ExprList *pOrderBy = p->pOrderBy;
int nOrderBy = p->pOrderBy->nExpr;
sqlite3 *db = pParse->db;
KeyInfo *pRet = sqlite3KeyInfoAlloc(db, nOrderBy+nExtra, 1);
if( pRet ){
int i;
for(i=0; i<nOrderBy; i++){
struct ExprList_item *pItem = &pOrderBy->a[i];
Expr *pTerm = pItem->pExpr;
CollSeq *pColl;
if( pTerm->flags & EP_Collate ){
pColl = sqlite3ExprCollSeq(pParse, pTerm);
}else{
pColl = multiSelectCollSeq(pParse, p, pItem->u.x.iOrderByCol-1);
if( pColl==0 ) pColl = db->pDfltColl;
pOrderBy->a[i].pExpr =
sqlite3ExprAddCollateString(pParse, pTerm, pColl->zName);
}
assert( sqlite3KeyInfoIsWriteable(pRet) );
pRet->aColl[i] = pColl;
pRet->aSortOrder[i] = pOrderBy->a[i].sortOrder;
}
}
return pRet;
}
#ifndef SQLITE_OMIT_CTE
/*
** This routine generates VDBE code to compute the content of a WITH RECURSIVE
** query of the form:
**
** <recursive-table> AS (<setup-query> UNION [ALL] <recursive-query>)
** \___________/ \_______________/
** p->pPrior p
**
**
** There is exactly one reference to the recursive-table in the FROM clause
** of recursive-query, marked with the SrcList->a[].fg.isRecursive flag.
**
** The setup-query runs once to generate an initial set of rows that go
** into a Queue table. Rows are extracted from the Queue table one by
** one. Each row extracted from Queue is output to pDest. Then the single
** extracted row (now in the iCurrent table) becomes the content of the
** recursive-table for a recursive-query run. The output of the recursive-query
** is added back into the Queue table. Then another row is extracted from Queue
** and the iteration continues until the Queue table is empty.
**
** If the compound query operator is UNION then no duplicate rows are ever
** inserted into the Queue table. The iDistinct table keeps a copy of all rows
** that have ever been inserted into Queue and causes duplicates to be
** discarded. If the operator is UNION ALL, then duplicates are allowed.
**
** If the query has an ORDER BY, then entries in the Queue table are kept in
** ORDER BY order and the first entry is extracted for each cycle. Without
** an ORDER BY, the Queue table is just a FIFO.
**
** If a LIMIT clause is provided, then the iteration stops after LIMIT rows
** have been output to pDest. A LIMIT of zero means to output no rows and a
** negative LIMIT means to output all rows. If there is also an OFFSET clause
** with a positive value, then the first OFFSET outputs are discarded rather
** than being sent to pDest. The LIMIT count does not begin until after OFFSET
** rows have been skipped.
*/
static void generateWithRecursiveQuery(
Parse *pParse, /* Parsing context */
Select *p, /* The recursive SELECT to be coded */
SelectDest *pDest /* What to do with query results */
){
SrcList *pSrc = p->pSrc; /* The FROM clause of the recursive query */
int nCol = p->pEList->nExpr; /* Number of columns in the recursive table */
Vdbe *v = pParse->pVdbe; /* The prepared statement under construction */
Select *pSetup = p->pPrior; /* The setup query */
int addrTop; /* Top of the loop */
int addrCont, addrBreak; /* CONTINUE and BREAK addresses */
int iCurrent = 0; /* The Current table */
int regCurrent; /* Register holding Current table */
int iQueue; /* The Queue table */
int iDistinct = 0; /* To ensure unique results if UNION */
int eDest = SRT_Fifo; /* How to write to Queue */
SelectDest destQueue; /* SelectDest targetting the Queue table */
int i; /* Loop counter */
int rc; /* Result code */
ExprList *pOrderBy; /* The ORDER BY clause */
Expr *pLimit; /* Saved LIMIT and OFFSET */
int regLimit, regOffset; /* Registers used by LIMIT and OFFSET */
/* Obtain authorization to do a recursive query */
if( sqlite3AuthCheck(pParse, SQLITE_RECURSIVE, 0, 0, 0) ) return;
/* Process the LIMIT and OFFSET clauses, if they exist */
addrBreak = sqlite3VdbeMakeLabel(v);
p->nSelectRow = 320; /* 4 billion rows */
computeLimitRegisters(pParse, p, addrBreak);
pLimit = p->pLimit;
regLimit = p->iLimit;
regOffset = p->iOffset;
p->pLimit = 0;
p->iLimit = p->iOffset = 0;
pOrderBy = p->pOrderBy;
/* Locate the cursor number of the Current table */
for(i=0; ALWAYS(i<pSrc->nSrc); i++){
if( pSrc->a[i].fg.isRecursive ){
iCurrent = pSrc->a[i].iCursor;
break;
}
}
/* Allocate cursors numbers for Queue and Distinct. The cursor number for
** the Distinct table must be exactly one greater than Queue in order
** for the SRT_DistFifo and SRT_DistQueue destinations to work. */
iQueue = pParse->nTab++;
if( p->op==TK_UNION ){
eDest = pOrderBy ? SRT_DistQueue : SRT_DistFifo;
iDistinct = pParse->nTab++;
}else{
eDest = pOrderBy ? SRT_Queue : SRT_Fifo;
}
sqlite3SelectDestInit(&destQueue, eDest, iQueue);
/* Allocate cursors for Current, Queue, and Distinct. */
regCurrent = ++pParse->nMem;
sqlite3VdbeAddOp3(v, OP_OpenPseudo, iCurrent, regCurrent, nCol);
if( pOrderBy ){
KeyInfo *pKeyInfo = multiSelectOrderByKeyInfo(pParse, p, 1);
sqlite3VdbeAddOp4(v, OP_OpenEphemeral, iQueue, pOrderBy->nExpr+2, 0,
(char*)pKeyInfo, P4_KEYINFO);
destQueue.pOrderBy = pOrderBy;
}else{
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iQueue, nCol);
}
VdbeComment((v, "Queue table"));
if( iDistinct ){
p->addrOpenEphm[0] = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iDistinct, 0);
p->selFlags |= SF_UsesEphemeral;
}
/* Detach the ORDER BY clause from the compound SELECT */
p->pOrderBy = 0;
/* Store the results of the setup-query in Queue. */
pSetup->pNext = 0;
ExplainQueryPlan((pParse, 1, "SETUP"));
rc = sqlite3Select(pParse, pSetup, &destQueue);
pSetup->pNext = p;
if( rc ) goto end_of_recursive_query;
/* Find the next row in the Queue and output that row */
addrTop = sqlite3VdbeAddOp2(v, OP_Rewind, iQueue, addrBreak); VdbeCoverage(v);
/* Transfer the next row in Queue over to Current */
sqlite3VdbeAddOp1(v, OP_NullRow, iCurrent); /* To reset column cache */
if( pOrderBy ){
sqlite3VdbeAddOp3(v, OP_Column, iQueue, pOrderBy->nExpr+1, regCurrent);
}else{
sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent);
}
sqlite3VdbeAddOp1(v, OP_Delete, iQueue);
/* Output the single row in Current */
addrCont = sqlite3VdbeMakeLabel(v);
codeOffset(v, regOffset, addrCont);
selectInnerLoop(pParse, p, iCurrent,
0, 0, pDest, addrCont, addrBreak);
if( regLimit ){
sqlite3VdbeAddOp2(v, OP_DecrJumpZero, regLimit, addrBreak);
VdbeCoverage(v);
}
sqlite3VdbeResolveLabel(v, addrCont);
/* Execute the recursive SELECT taking the single row in Current as
** the value for the recursive-table. Store the results in the Queue.
*/
if( p->selFlags & SF_Aggregate ){
sqlite3ErrorMsg(pParse, "recursive aggregate queries not supported");
}else{
p->pPrior = 0;
ExplainQueryPlan((pParse, 1, "RECURSIVE STEP"));
sqlite3Select(pParse, p, &destQueue);
assert( p->pPrior==0 );
p->pPrior = pSetup;
}
/* Keep running the loop until the Queue is empty */
sqlite3VdbeGoto(v, addrTop);
sqlite3VdbeResolveLabel(v, addrBreak);
end_of_recursive_query:
sqlite3ExprListDelete(pParse->db, p->pOrderBy);
p->pOrderBy = pOrderBy;
p->pLimit = pLimit;
return;
}
#endif /* SQLITE_OMIT_CTE */
/* Forward references */
static int multiSelectOrderBy(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
);
/*
** Handle the special case of a compound-select that originates from a
** VALUES clause. By handling this as a special case, we avoid deep
** recursion, and thus do not need to enforce the SQLITE_LIMIT_COMPOUND_SELECT
** on a VALUES clause.
**
** Because the Select object originates from a VALUES clause:
** (1) There is no LIMIT or OFFSET or else there is a LIMIT of exactly 1
** (2) All terms are UNION ALL
** (3) There is no ORDER BY clause
**
** The "LIMIT of exactly 1" case of condition (1) comes about when a VALUES
** clause occurs within scalar expression (ex: "SELECT (VALUES(1),(2),(3))").
** The sqlite3CodeSubselect will have added the LIMIT 1 clause in tht case.
** Since the limit is exactly 1, we only need to evalutes the left-most VALUES.
*/
static int multiSelectValues(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
){
int nRow = 1;
int rc = 0;
int bShowAll = p->pLimit==0;
assert( p->selFlags & SF_MultiValue );
do{
assert( p->selFlags & SF_Values );
assert( p->op==TK_ALL || (p->op==TK_SELECT && p->pPrior==0) );
assert( p->pNext==0 || p->pEList->nExpr==p->pNext->pEList->nExpr );
if( p->pPrior==0 ) break;
assert( p->pPrior->pNext==p );
p = p->pPrior;
nRow += bShowAll;
}while(1);
ExplainQueryPlan((pParse, 0, "SCAN %d CONSTANT ROW%s", nRow,
nRow==1 ? "" : "S"));
while( p ){
selectInnerLoop(pParse, p, -1, 0, 0, pDest, 1, 1);
if( !bShowAll ) break;
p->nSelectRow = nRow;
p = p->pNext;
}
return rc;
}
/*
** This routine is called to process a compound query form from
** two or more separate queries using UNION, UNION ALL, EXCEPT, or
** INTERSECT
**
** "p" points to the right-most of the two queries. the query on the
** left is p->pPrior. The left query could also be a compound query
** in which case this routine will be called recursively.
**
** The results of the total query are to be written into a destination
** of type eDest with parameter iParm.
**
** Example 1: Consider a three-way compound SQL statement.
**
** SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3
**
** This statement is parsed up as follows:
**
** SELECT c FROM t3
** |
** `-----> SELECT b FROM t2
** |
** `------> SELECT a FROM t1
**
** The arrows in the diagram above represent the Select.pPrior pointer.
** So if this routine is called with p equal to the t3 query, then
** pPrior will be the t2 query. p->op will be TK_UNION in this case.
**
** Notice that because of the way SQLite parses compound SELECTs, the
** individual selects always group from left to right.
*/
static int multiSelect(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
){
int rc = SQLITE_OK; /* Success code from a subroutine */
Select *pPrior; /* Another SELECT immediately to our left */
Vdbe *v; /* Generate code to this VDBE */
SelectDest dest; /* Alternative data destination */
Select *pDelete = 0; /* Chain of simple selects to delete */
sqlite3 *db; /* Database connection */
/* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only
** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
*/
assert( p && p->pPrior ); /* Calling function guarantees this much */
assert( (p->selFlags & SF_Recursive)==0 || p->op==TK_ALL || p->op==TK_UNION );
db = pParse->db;
pPrior = p->pPrior;
dest = *pDest;
if( pPrior->pOrderBy || pPrior->pLimit ){
sqlite3ErrorMsg(pParse,"%s clause should come after %s not before",
pPrior->pOrderBy!=0 ? "ORDER BY" : "LIMIT", selectOpName(p->op));
rc = 1;
goto multi_select_end;
}
v = sqlite3GetVdbe(pParse);
assert( v!=0 ); /* The VDBE already created by calling function */
/* Create the destination temporary table if necessary
*/
if( dest.eDest==SRT_EphemTab ){
assert( p->pEList );
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iSDParm, p->pEList->nExpr);
dest.eDest = SRT_Table;
}
/* Special handling for a compound-select that originates as a VALUES clause.
*/
if( p->selFlags & SF_MultiValue ){
rc = multiSelectValues(pParse, p, &dest);
goto multi_select_end;
}
/* Make sure all SELECTs in the statement have the same number of elements
** in their result sets.
*/
assert( p->pEList && pPrior->pEList );
assert( p->pEList->nExpr==pPrior->pEList->nExpr );
#ifndef SQLITE_OMIT_CTE
if( p->selFlags & SF_Recursive ){
generateWithRecursiveQuery(pParse, p, &dest);
}else
#endif
/* Compound SELECTs that have an ORDER BY clause are handled separately.
*/
if( p->pOrderBy ){
return multiSelectOrderBy(pParse, p, pDest);
}else{
#ifndef SQLITE_OMIT_EXPLAIN
if( pPrior->pPrior==0 ){
ExplainQueryPlan((pParse, 1, "COMPOUND QUERY"));
ExplainQueryPlan((pParse, 1, "LEFT-MOST SUBQUERY"));
}
#endif
/* Generate code for the left and right SELECT statements.
*/
switch( p->op ){
case TK_ALL: {
int addr = 0;
int nLimit;
assert( !pPrior->pLimit );
pPrior->iLimit = p->iLimit;
pPrior->iOffset = p->iOffset;
pPrior->pLimit = p->pLimit;
rc = sqlite3Select(pParse, pPrior, &dest);
p->pLimit = 0;
if( rc ){
goto multi_select_end;
}
p->pPrior = 0;
p->iLimit = pPrior->iLimit;
p->iOffset = pPrior->iOffset;
if( p->iLimit ){
addr = sqlite3VdbeAddOp1(v, OP_IfNot, p->iLimit); VdbeCoverage(v);
VdbeComment((v, "Jump ahead if LIMIT reached"));
if( p->iOffset ){
sqlite3VdbeAddOp3(v, OP_OffsetLimit,
p->iLimit, p->iOffset+1, p->iOffset);
}
}
ExplainQueryPlan((pParse, 1, "UNION ALL"));
rc = sqlite3Select(pParse, p, &dest);
testcase( rc!=SQLITE_OK );
pDelete = p->pPrior;
p->pPrior = pPrior;
p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
if( pPrior->pLimit
&& sqlite3ExprIsInteger(pPrior->pLimit->pLeft, &nLimit)
&& nLimit>0 && p->nSelectRow > sqlite3LogEst((u64)nLimit)
){
p->nSelectRow = sqlite3LogEst((u64)nLimit);
}
if( addr ){
sqlite3VdbeJumpHere(v, addr);
}
break;
}
case TK_EXCEPT:
case TK_UNION: {
int unionTab; /* Cursor number of the temp table holding result */
u8 op = 0; /* One of the SRT_ operations to apply to self */
int priorOp; /* The SRT_ operation to apply to prior selects */
Expr *pLimit; /* Saved values of p->nLimit */
int addr;
SelectDest uniondest;
testcase( p->op==TK_EXCEPT );
testcase( p->op==TK_UNION );
priorOp = SRT_Union;
if( dest.eDest==priorOp ){
/* We can reuse a temporary table generated by a SELECT to our
** right.
*/
assert( p->pLimit==0 ); /* Not allowed on leftward elements */
unionTab = dest.iSDParm;
}else{
/* We will need to create our own temporary table to hold the
** intermediate results.
*/
unionTab = pParse->nTab++;
assert( p->pOrderBy==0 );
addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, unionTab, 0);
assert( p->addrOpenEphm[0] == -1 );
p->addrOpenEphm[0] = addr;
findRightmost(p)->selFlags |= SF_UsesEphemeral;
assert( p->pEList );
}
/* Code the SELECT statements to our left
*/
assert( !pPrior->pOrderBy );
sqlite3SelectDestInit(&uniondest, priorOp, unionTab);
rc = sqlite3Select(pParse, pPrior, &uniondest);
if( rc ){
goto multi_select_end;
}
/* Code the current SELECT statement
*/
if( p->op==TK_EXCEPT ){
op = SRT_Except;
}else{
assert( p->op==TK_UNION );
op = SRT_Union;
}
p->pPrior = 0;
pLimit = p->pLimit;
p->pLimit = 0;
uniondest.eDest = op;
ExplainQueryPlan((pParse, 1, "%s USING TEMP B-TREE",
selectOpName(p->op)));
rc = sqlite3Select(pParse, p, &uniondest);
testcase( rc!=SQLITE_OK );
/* Query flattening in sqlite3Select() might refill p->pOrderBy.
** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */
sqlite3ExprListDelete(db, p->pOrderBy);
pDelete = p->pPrior;
p->pPrior = pPrior;
p->pOrderBy = 0;
if( p->op==TK_UNION ){
p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
}
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = pLimit;
p->iLimit = 0;
p->iOffset = 0;
/* Convert the data in the temporary table into whatever form
** it is that we currently need.
*/
assert( unionTab==dest.iSDParm || dest.eDest!=priorOp );
if( dest.eDest!=priorOp ){
int iCont, iBreak, iStart;
assert( p->pEList );
iBreak = sqlite3VdbeMakeLabel(v);
iCont = sqlite3VdbeMakeLabel(v);
computeLimitRegisters(pParse, p, iBreak);
sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak); VdbeCoverage(v);
iStart = sqlite3VdbeCurrentAddr(v);
selectInnerLoop(pParse, p, unionTab,
0, 0, &dest, iCont, iBreak);
sqlite3VdbeResolveLabel(v, iCont);
sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); VdbeCoverage(v);
sqlite3VdbeResolveLabel(v, iBreak);
sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
}
break;
}
default: assert( p->op==TK_INTERSECT ); {
int tab1, tab2;
int iCont, iBreak, iStart;
Expr *pLimit;
int addr;
SelectDest intersectdest;
int r1;
/* INTERSECT is different from the others since it requires
** two temporary tables. Hence it has its own case. Begin
** by allocating the tables we will need.
*/
tab1 = pParse->nTab++;
tab2 = pParse->nTab++;
assert( p->pOrderBy==0 );
addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab1, 0);
assert( p->addrOpenEphm[0] == -1 );
p->addrOpenEphm[0] = addr;
findRightmost(p)->selFlags |= SF_UsesEphemeral;
assert( p->pEList );
/* Code the SELECTs to our left into temporary table "tab1".
*/
sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1);
rc = sqlite3Select(pParse, pPrior, &intersectdest);
if( rc ){
goto multi_select_end;
}
/* Code the current SELECT into temporary table "tab2"
*/
addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0);
assert( p->addrOpenEphm[1] == -1 );
p->addrOpenEphm[1] = addr;
p->pPrior = 0;
pLimit = p->pLimit;
p->pLimit = 0;
intersectdest.iSDParm = tab2;
ExplainQueryPlan((pParse, 1, "%s USING TEMP B-TREE",
selectOpName(p->op)));
rc = sqlite3Select(pParse, p, &intersectdest);
testcase( rc!=SQLITE_OK );
pDelete = p->pPrior;
p->pPrior = pPrior;
if( p->nSelectRow>pPrior->nSelectRow ){
p->nSelectRow = pPrior->nSelectRow;
}
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = pLimit;
/* Generate code to take the intersection of the two temporary
** tables.
*/
assert( p->pEList );
iBreak = sqlite3VdbeMakeLabel(v);
iCont = sqlite3VdbeMakeLabel(v);
computeLimitRegisters(pParse, p, iBreak);
sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak); VdbeCoverage(v);
r1 = sqlite3GetTempReg(pParse);
iStart = sqlite3VdbeAddOp2(v, OP_RowData, tab1, r1);
sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0);
VdbeCoverage(v);
sqlite3ReleaseTempReg(pParse, r1);
selectInnerLoop(pParse, p, tab1,
0, 0, &dest, iCont, iBreak);
sqlite3VdbeResolveLabel(v, iCont);
sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); VdbeCoverage(v);
sqlite3VdbeResolveLabel(v, iBreak);
sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
break;
}
}
#ifndef SQLITE_OMIT_EXPLAIN
if( p->pNext==0 ){
ExplainQueryPlanPop(pParse);
}
#endif
}
/* Compute collating sequences used by
** temporary tables needed to implement the compound select.
** Attach the KeyInfo structure to all temporary tables.
**
** This section is run by the right-most SELECT statement only.
** SELECT statements to the left always skip this part. The right-most
** SELECT might also skip this part if it has no ORDER BY clause and
** no temp tables are required.
*/
if( p->selFlags & SF_UsesEphemeral ){
int i; /* Loop counter */
KeyInfo *pKeyInfo; /* Collating sequence for the result set */
Select *pLoop; /* For looping through SELECT statements */
CollSeq **apColl; /* For looping through pKeyInfo->aColl[] */
int nCol; /* Number of columns in result set */
assert( p->pNext==0 );
nCol = p->pEList->nExpr;
pKeyInfo = sqlite3KeyInfoAlloc(db, nCol, 1);
if( !pKeyInfo ){
rc = SQLITE_NOMEM_BKPT;
goto multi_select_end;
}
for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
*apColl = multiSelectCollSeq(pParse, p, i);
if( 0==*apColl ){
*apColl = db->pDfltColl;
}
}
for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
for(i=0; i<2; i++){
int addr = pLoop->addrOpenEphm[i];
if( addr<0 ){
/* If [0] is unused then [1] is also unused. So we can
** always safely abort as soon as the first unused slot is found */
assert( pLoop->addrOpenEphm[1]<0 );
break;
}
sqlite3VdbeChangeP2(v, addr, nCol);
sqlite3VdbeChangeP4(v, addr, (char*)sqlite3KeyInfoRef(pKeyInfo),
P4_KEYINFO);
pLoop->addrOpenEphm[i] = -1;
}
}
sqlite3KeyInfoUnref(pKeyInfo);
}
multi_select_end:
pDest->iSdst = dest.iSdst;
pDest->nSdst = dest.nSdst;
sqlite3SelectDelete(db, pDelete);
return rc;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */
/*
** Error message for when two or more terms of a compound select have different
** size result sets.
*/
void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p){
if( p->selFlags & SF_Values ){
sqlite3ErrorMsg(pParse, "all VALUES must have the same number of terms");
}else{
sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
" do not have the same number of result columns", selectOpName(p->op));
}
}
/*
** Code an output subroutine for a coroutine implementation of a
** SELECT statment.
**
** The data to be output is contained in pIn->iSdst. There are
** pIn->nSdst columns to be output. pDest is where the output should
** be sent.
**
** regReturn is the number of the register holding the subroutine
** return address.
**
** If regPrev>0 then it is the first register in a vector that
** records the previous output. mem[regPrev] is a flag that is false
** if there has been no previous output. If regPrev>0 then code is
** generated to suppress duplicates. pKeyInfo is used for comparing
** keys.
**
** If the LIMIT found in p->iLimit is reached, jump immediately to
** iBreak.
*/
static int generateOutputSubroutine(
Parse *pParse, /* Parsing context */
Select *p, /* The SELECT statement */
SelectDest *pIn, /* Coroutine supplying data */
SelectDest *pDest, /* Where to send the data */
int regReturn, /* The return address register */
int regPrev, /* Previous result register. No uniqueness if 0 */
KeyInfo *pKeyInfo, /* For comparing with previous entry */
int iBreak /* Jump here if we hit the LIMIT */
){
Vdbe *v = pParse->pVdbe;
int iContinue;
int addr;
addr = sqlite3VdbeCurrentAddr(v);
iContinue = sqlite3VdbeMakeLabel(v);
/* Suppress duplicates for UNION, EXCEPT, and INTERSECT
*/
if( regPrev ){
int addr1, addr2;
addr1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev); VdbeCoverage(v);
addr2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iSdst, regPrev+1, pIn->nSdst,
(char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO);
sqlite3VdbeAddOp3(v, OP_Jump, addr2+2, iContinue, addr2+2); VdbeCoverage(v);
sqlite3VdbeJumpHere(v, addr1);
sqlite3VdbeAddOp3(v, OP_Copy, pIn->iSdst, regPrev+1, pIn->nSdst-1);
sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev);
}
if( pParse->db->mallocFailed ) return 0;
/* Suppress the first OFFSET entries if there is an OFFSET clause
*/
codeOffset(v, p->iOffset, iContinue);
assert( pDest->eDest!=SRT_Exists );
assert( pDest->eDest!=SRT_Table );
switch( pDest->eDest ){
/* Store the result as data using a unique key.
*/
case SRT_EphemTab: {
int r1 = sqlite3GetTempReg(pParse);
int r2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iSdst, pIn->nSdst, r1);
sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iSDParm, r2);
sqlite3VdbeAddOp3(v, OP_Insert, pDest->iSDParm, r1, r2);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
sqlite3ReleaseTempReg(pParse, r2);
sqlite3ReleaseTempReg(pParse, r1);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
/* If we are creating a set for an "expr IN (SELECT ...)".
*/
case SRT_Set: {
int r1;
testcase( pIn->nSdst>1 );
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iSdst, pIn->nSdst,
r1, pDest->zAffSdst, pIn->nSdst);
sqlite3ExprCacheAffinityChange(pParse, pIn->iSdst, pIn->nSdst);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, pDest->iSDParm, r1,
pIn->iSdst, pIn->nSdst);
sqlite3ReleaseTempReg(pParse, r1);
break;
}
/* If this is a scalar select that is part of an expression, then
** store the results in the appropriate memory cell and break out
** of the scan loop.
*/
case SRT_Mem: {
assert( pIn->nSdst==1 || pParse->nErr>0 ); testcase( pIn->nSdst!=1 );
sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSDParm, 1);
/* The LIMIT clause will jump out of the loop for us */
break;
}
#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
/* The results are stored in a sequence of registers
** starting at pDest->iSdst. Then the co-routine yields.
*/
case SRT_Coroutine: {
if( pDest->iSdst==0 ){
pDest->iSdst = sqlite3GetTempRange(pParse, pIn->nSdst);
pDest->nSdst = pIn->nSdst;
}
sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSdst, pIn->nSdst);
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
break;
}
/* If none of the above, then the result destination must be
** SRT_Output. This routine is never called with any other
** destination other than the ones handled above or SRT_Output.
**
** For SRT_Output, results are stored in a sequence of registers.
** Then the OP_ResultRow opcode is used to cause sqlite3_step() to
** return the next row of result.
*/
default: {
assert( pDest->eDest==SRT_Output );
sqlite3VdbeAddOp2(v, OP_ResultRow, pIn->iSdst, pIn->nSdst);
sqlite3ExprCacheAffinityChange(pParse, pIn->iSdst, pIn->nSdst);
break;
}
}
/* Jump to the end of the loop if the LIMIT is reached.
*/
if( p->iLimit ){
sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v);
}
/* Generate the subroutine return
*/
sqlite3VdbeResolveLabel(v, iContinue);
sqlite3VdbeAddOp1(v, OP_Return, regReturn);
return addr;
}
/*
** Alternative compound select code generator for cases when there
** is an ORDER BY clause.
**
** We assume a query of the following form:
**
** <selectA> <operator> <selectB> ORDER BY <orderbylist>
**
** <operator> is one of UNION ALL, UNION, EXCEPT, or INTERSECT. The idea
** is to code both <selectA> and <selectB> with the ORDER BY clause as
** co-routines. Then run the co-routines in parallel and merge the results
** into the output. In addition to the two coroutines (called selectA and
** selectB) there are 7 subroutines:
**
** outA: Move the output of the selectA coroutine into the output
** of the compound query.
**
** outB: Move the output of the selectB coroutine into the output
** of the compound query. (Only generated for UNION and
** UNION ALL. EXCEPT and INSERTSECT never output a row that
** appears only in B.)
**
** AltB: Called when there is data from both coroutines and A<B.
**
** AeqB: Called when there is data from both coroutines and A==B.
**
** AgtB: Called when there is data from both coroutines and A>B.
**
** EofA: Called when data is exhausted from selectA.
**
** EofB: Called when data is exhausted from selectB.
**
** The implementation of the latter five subroutines depend on which
** <operator> is used:
**
**
** UNION ALL UNION EXCEPT INTERSECT
** ------------- ----------------- -------------- -----------------
** AltB: outA, nextA outA, nextA outA, nextA nextA
**
** AeqB: outA, nextA nextA nextA outA, nextA
**
** AgtB: outB, nextB outB, nextB nextB nextB
**
** EofA: outB, nextB outB, nextB halt halt
**
** EofB: outA, nextA outA, nextA outA, nextA halt
**
** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA
** causes an immediate jump to EofA and an EOF on B following nextB causes
** an immediate jump to EofB. Within EofA and EofB, and EOF on entry or
** following nextX causes a jump to the end of the select processing.
**
** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled
** within the output subroutine. The regPrev register set holds the previously
** output value. A comparison is made against this value and the output
** is skipped if the next results would be the same as the previous.
**
** The implementation plan is to implement the two coroutines and seven
** subroutines first, then put the control logic at the bottom. Like this:
**
** goto Init
** coA: coroutine for left query (A)
** coB: coroutine for right query (B)
** outA: output one row of A
** outB: output one row of B (UNION and UNION ALL only)
** EofA: ...
** EofB: ...
** AltB: ...
** AeqB: ...
** AgtB: ...
** Init: initialize coroutine registers
** yield coA
** if eof(A) goto EofA
** yield coB
** if eof(B) goto EofB
** Cmpr: Compare A, B
** Jump AltB, AeqB, AgtB
** End: ...
**
** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not
** actually called using Gosub and they do not Return. EofA and EofB loop
** until all data is exhausted then jump to the "end" labe. AltB, AeqB,
** and AgtB jump to either L2 or to one of EofA or EofB.
*/
#ifndef SQLITE_OMIT_COMPOUND_SELECT
static int multiSelectOrderBy(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
){
int i, j; /* Loop counters */
Select *pPrior; /* Another SELECT immediately to our left */
Vdbe *v; /* Generate code to this VDBE */
SelectDest destA; /* Destination for coroutine A */
SelectDest destB; /* Destination for coroutine B */
int regAddrA; /* Address register for select-A coroutine */
int regAddrB; /* Address register for select-B coroutine */
int addrSelectA; /* Address of the select-A coroutine */
int addrSelectB; /* Address of the select-B coroutine */
int regOutA; /* Address register for the output-A subroutine */
int regOutB; /* Address register for the output-B subroutine */
int addrOutA; /* Address of the output-A subroutine */
int addrOutB = 0; /* Address of the output-B subroutine */
int addrEofA; /* Address of the select-A-exhausted subroutine */
int addrEofA_noB; /* Alternate addrEofA if B is uninitialized */
int addrEofB; /* Address of the select-B-exhausted subroutine */
int addrAltB; /* Address of the A<B subroutine */
int addrAeqB; /* Address of the A==B subroutine */
int addrAgtB; /* Address of the A>B subroutine */
int regLimitA; /* Limit register for select-A */
int regLimitB; /* Limit register for select-A */
int regPrev; /* A range of registers to hold previous output */
int savedLimit; /* Saved value of p->iLimit */
int savedOffset; /* Saved value of p->iOffset */
int labelCmpr; /* Label for the start of the merge algorithm */
int labelEnd; /* Label for the end of the overall SELECT stmt */
int addr1; /* Jump instructions that get retargetted */
int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */
KeyInfo *pKeyMerge; /* Comparison information for merging rows */
sqlite3 *db; /* Database connection */
ExprList *pOrderBy; /* The ORDER BY clause */
int nOrderBy; /* Number of terms in the ORDER BY clause */
int *aPermute; /* Mapping from ORDER BY terms to result set columns */
assert( p->pOrderBy!=0 );
assert( pKeyDup==0 ); /* "Managed" code needs this. Ticket #3382. */
db = pParse->db;
v = pParse->pVdbe;
assert( v!=0 ); /* Already thrown the error if VDBE alloc failed */
labelEnd = sqlite3VdbeMakeLabel(v);
labelCmpr = sqlite3VdbeMakeLabel(v);
/* Patch up the ORDER BY clause
*/
op = p->op;
pPrior = p->pPrior;
assert( pPrior->pOrderBy==0 );
pOrderBy = p->pOrderBy;
assert( pOrderBy );
nOrderBy = pOrderBy->nExpr;
/* For operators other than UNION ALL we have to make sure that
** the ORDER BY clause covers every term of the result set. Add
** terms to the ORDER BY clause as necessary.
*/
if( op!=TK_ALL ){
for(i=1; db->mallocFailed==0 && i<=p->pEList->nExpr; i++){
struct ExprList_item *pItem;
for(j=0, pItem=pOrderBy->a; j<nOrderBy; j++, pItem++){
assert( pItem->u.x.iOrderByCol>0 );
if( pItem->u.x.iOrderByCol==i ) break;
}
if( j==nOrderBy ){
Expr *pNew = sqlite3Expr(db, TK_INTEGER, 0);
if( pNew==0 ) return SQLITE_NOMEM_BKPT;
pNew->flags |= EP_IntValue;
pNew->u.iValue = i;
p->pOrderBy = pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew);
if( pOrderBy ) pOrderBy->a[nOrderBy++].u.x.iOrderByCol = (u16)i;
}
}
}
/* Compute the comparison permutation and keyinfo that is used with
** the permutation used to determine if the next
** row of results comes from selectA or selectB. Also add explicit
** collations to the ORDER BY clause terms so that when the subqueries
** to the right and the left are evaluated, they use the correct
** collation.
*/
aPermute = sqlite3DbMallocRawNN(db, sizeof(int)*(nOrderBy + 1));
if( aPermute ){
struct ExprList_item *pItem;
aPermute[0] = nOrderBy;
for(i=1, pItem=pOrderBy->a; i<=nOrderBy; i++, pItem++){
assert( pItem->u.x.iOrderByCol>0 );
assert( pItem->u.x.iOrderByCol<=p->pEList->nExpr );
aPermute[i] = pItem->u.x.iOrderByCol - 1;
}
pKeyMerge = multiSelectOrderByKeyInfo(pParse, p, 1);
}else{
pKeyMerge = 0;
}
/* Reattach the ORDER BY clause to the query.
*/
p->pOrderBy = pOrderBy;
pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy, 0);
/* Allocate a range of temporary registers and the KeyInfo needed
** for the logic that removes duplicate result rows when the
** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL).
*/
if( op==TK_ALL ){
regPrev = 0;
}else{
int nExpr = p->pEList->nExpr;
assert( nOrderBy>=nExpr || db->mallocFailed );
regPrev = pParse->nMem+1;
pParse->nMem += nExpr+1;
sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev);
pKeyDup = sqlite3KeyInfoAlloc(db, nExpr, 1);
if( pKeyDup ){
assert( sqlite3KeyInfoIsWriteable(pKeyDup) );
for(i=0; i<nExpr; i++){
pKeyDup->aColl[i] = multiSelectCollSeq(pParse, p, i);
pKeyDup->aSortOrder[i] = 0;
}
}
}
/* Separate the left and the right query from one another
*/
p->pPrior = 0;
pPrior->pNext = 0;
sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER");
if( pPrior->pPrior==0 ){
sqlite3ResolveOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, "ORDER");
}
/* Compute the limit registers */
computeLimitRegisters(pParse, p, labelEnd);
if( p->iLimit && op==TK_ALL ){
regLimitA = ++pParse->nMem;
regLimitB = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Copy, p->iOffset ? p->iOffset+1 : p->iLimit,
regLimitA);
sqlite3VdbeAddOp2(v, OP_Copy, regLimitA, regLimitB);
}else{
regLimitA = regLimitB = 0;
}
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = 0;
regAddrA = ++pParse->nMem;
regAddrB = ++pParse->nMem;
regOutA = ++pParse->nMem;
regOutB = ++pParse->nMem;
sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);
ExplainQueryPlan((pParse, 1, "MERGE (%s)", selectOpName(p->op)));
/* Generate a coroutine to evaluate the SELECT statement to the
** left of the compound operator - the "A" select.
*/
addrSelectA = sqlite3VdbeCurrentAddr(v) + 1;
addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrA, 0, addrSelectA);
VdbeComment((v, "left SELECT"));
pPrior->iLimit = regLimitA;
ExplainQueryPlan((pParse, 1, "LEFT"));
sqlite3Select(pParse, pPrior, &destA);
sqlite3VdbeEndCoroutine(v, regAddrA);
sqlite3VdbeJumpHere(v, addr1);
/* Generate a coroutine to evaluate the SELECT statement on
** the right - the "B" select
*/
addrSelectB = sqlite3VdbeCurrentAddr(v) + 1;
addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrB, 0, addrSelectB);
VdbeComment((v, "right SELECT"));
savedLimit = p->iLimit;
savedOffset = p->iOffset;
p->iLimit = regLimitB;
p->iOffset = 0;
ExplainQueryPlan((pParse, 1, "RIGHT"));
sqlite3Select(pParse, p, &destB);
p->iLimit = savedLimit;
p->iOffset = savedOffset;
sqlite3VdbeEndCoroutine(v, regAddrB);
/* Generate a subroutine that outputs the current row of the A
** select as the next output row of the compound select.
*/
VdbeNoopComment((v, "Output routine for A"));
addrOutA = generateOutputSubroutine(pParse,
p, &destA, pDest, regOutA,
regPrev, pKeyDup, labelEnd);
/* Generate a subroutine that outputs the current row of the B
** select as the next output row of the compound select.
*/
if( op==TK_ALL || op==TK_UNION ){
VdbeNoopComment((v, "Output routine for B"));
addrOutB = generateOutputSubroutine(pParse,
p, &destB, pDest, regOutB,
regPrev, pKeyDup, labelEnd);
}
sqlite3KeyInfoUnref(pKeyDup);
/* Generate a subroutine to run when the results from select A
** are exhausted and only data in select B remains.
*/
if( op==TK_EXCEPT || op==TK_INTERSECT ){
addrEofA_noB = addrEofA = labelEnd;
}else{
VdbeNoopComment((v, "eof-A subroutine"));
addrEofA = sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
addrEofA_noB = sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, labelEnd);
VdbeCoverage(v);
sqlite3VdbeGoto(v, addrEofA);
p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
}
/* Generate a subroutine to run when the results from select B
** are exhausted and only data in select A remains.
*/
if( op==TK_INTERSECT ){
addrEofB = addrEofA;
if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
}else{
VdbeNoopComment((v, "eof-B subroutine"));
addrEofB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, labelEnd); VdbeCoverage(v);
sqlite3VdbeGoto(v, addrEofB);
}
/* Generate code to handle the case of A<B
*/
VdbeNoopComment((v, "A-lt-B subroutine"));
addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA); VdbeCoverage(v);
sqlite3VdbeGoto(v, labelCmpr);
/* Generate code to handle the case of A==B
*/
if( op==TK_ALL ){
addrAeqB = addrAltB;
}else if( op==TK_INTERSECT ){
addrAeqB = addrAltB;
addrAltB++;
}else{
VdbeNoopComment((v, "A-eq-B subroutine"));
addrAeqB =
sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA); VdbeCoverage(v);
sqlite3VdbeGoto(v, labelCmpr);
}
/* Generate code to handle the case of A>B
*/
VdbeNoopComment((v, "A-gt-B subroutine"));
addrAgtB = sqlite3VdbeCurrentAddr(v);
if( op==TK_ALL || op==TK_UNION ){
sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
}
sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v);
sqlite3VdbeGoto(v, labelCmpr);
/* This code runs once to initialize everything.
*/
sqlite3VdbeJumpHere(v, addr1);
sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA_noB); VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v);
/* Implement the main merge loop
*/
sqlite3VdbeResolveLabel(v, labelCmpr);
sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY);
sqlite3VdbeAddOp4(v, OP_Compare, destA.iSdst, destB.iSdst, nOrderBy,
(char*)pKeyMerge, P4_KEYINFO);
sqlite3VdbeChangeP5(v, OPFLAG_PERMUTE);
sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB); VdbeCoverage(v);
/* Jump to the this point in order to terminate the query.
*/
sqlite3VdbeResolveLabel(v, labelEnd);
/* Reassembly the compound query so that it will be freed correctly
** by the calling function */
if( p->pPrior ){
sqlite3SelectDelete(db, p->pPrior);
}
p->pPrior = pPrior;
pPrior->pNext = p;
/*** TBD: Insert subroutine calls to close cursors on incomplete
**** subqueries ****/
ExplainQueryPlanPop(pParse);
return pParse->nErr!=0;
}
#endif
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/* An instance of the SubstContext object describes an substitution edit
** to be performed on a parse tree.
**
** All references to columns in table iTable are to be replaced by corresponding
** expressions in pEList.
*/
typedef struct SubstContext {
Parse *pParse; /* The parsing context */
int iTable; /* Replace references to this table */
int iNewTable; /* New table number */
int isLeftJoin; /* Add TK_IF_NULL_ROW opcodes on each replacement */
ExprList *pEList; /* Replacement expressions */
} SubstContext;
/* Forward Declarations */
static void substExprList(SubstContext*, ExprList*);
static void substSelect(SubstContext*, Select*, int);
/*
** Scan through the expression pExpr. Replace every reference to
** a column in table number iTable with a copy of the iColumn-th
** entry in pEList. (But leave references to the ROWID column
** unchanged.)
**
** This routine is part of the flattening procedure. A subquery
** whose result set is defined by pEList appears as entry in the
** FROM clause of a SELECT such that the VDBE cursor assigned to that
** FORM clause entry is iTable. This routine makes the necessary
** changes to pExpr so that it refers directly to the source table
** of the subquery rather the result set of the subquery.
*/
static Expr *substExpr(
SubstContext *pSubst, /* Description of the substitution */
Expr *pExpr /* Expr in which substitution occurs */
){
if( pExpr==0 ) return 0;
if( ExprHasProperty(pExpr, EP_FromJoin)
&& pExpr->iRightJoinTable==pSubst->iTable
){
pExpr->iRightJoinTable = pSubst->iNewTable;
}
if( pExpr->op==TK_COLUMN && pExpr->iTable==pSubst->iTable ){
if( pExpr->iColumn<0 ){
pExpr->op = TK_NULL;
}else{
Expr *pNew;
Expr *pCopy = pSubst->pEList->a[pExpr->iColumn].pExpr;
Expr ifNullRow;
assert( pSubst->pEList!=0 && pExpr->iColumn<pSubst->pEList->nExpr );
assert( pExpr->pLeft==0 && pExpr->pRight==0 );
if( sqlite3ExprIsVector(pCopy) ){
sqlite3VectorErrorMsg(pSubst->pParse, pCopy);
}else{
sqlite3 *db = pSubst->pParse->db;
if( pSubst->isLeftJoin && pCopy->op!=TK_COLUMN ){
memset(&ifNullRow, 0, sizeof(ifNullRow));
ifNullRow.op = TK_IF_NULL_ROW;
ifNullRow.pLeft = pCopy;
ifNullRow.iTable = pSubst->iNewTable;
pCopy = &ifNullRow;
}
pNew = sqlite3ExprDup(db, pCopy, 0);
if( pNew && pSubst->isLeftJoin ){
ExprSetProperty(pNew, EP_CanBeNull);
}
if( pNew && ExprHasProperty(pExpr,EP_FromJoin) ){
pNew->iRightJoinTable = pExpr->iRightJoinTable;
ExprSetProperty(pNew, EP_FromJoin);
}
sqlite3ExprDelete(db, pExpr);
pExpr = pNew;
}
}
}else{
if( pExpr->op==TK_IF_NULL_ROW && pExpr->iTable==pSubst->iTable ){
pExpr->iTable = pSubst->iNewTable;
}
pExpr->pLeft = substExpr(pSubst, pExpr->pLeft);
pExpr->pRight = substExpr(pSubst, pExpr->pRight);
if( ExprHasProperty(pExpr, EP_xIsSelect) ){
substSelect(pSubst, pExpr->x.pSelect, 1);
}else{
substExprList(pSubst, pExpr->x.pList);
}
}
return pExpr;
}
static void substExprList(
SubstContext *pSubst, /* Description of the substitution */
ExprList *pList /* List to scan and in which to make substitutes */
){
int i;
if( pList==0 ) return;
for(i=0; i<pList->nExpr; i++){
pList->a[i].pExpr = substExpr(pSubst, pList->a[i].pExpr);
}
}
static void substSelect(
SubstContext *pSubst, /* Description of the substitution */
Select *p, /* SELECT statement in which to make substitutions */
int doPrior /* Do substitutes on p->pPrior too */
){
SrcList *pSrc;
struct SrcList_item *pItem;
int i;
if( !p ) return;
do{
substExprList(pSubst, p->pEList);
substExprList(pSubst, p->pGroupBy);
substExprList(pSubst, p->pOrderBy);
p->pHaving = substExpr(pSubst, p->pHaving);
p->pWhere = substExpr(pSubst, p->pWhere);
pSrc = p->pSrc;
assert( pSrc!=0 );
for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
substSelect(pSubst, pItem->pSelect, 1);
if( pItem->fg.isTabFunc ){
substExprList(pSubst, pItem->u1.pFuncArg);
}
}
}while( doPrior && (p = p->pPrior)!=0 );
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** This routine attempts to flatten subqueries as a performance optimization.
** This routine returns 1 if it makes changes and 0 if no flattening occurs.
**
** To understand the concept of flattening, consider the following
** query:
**
** SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5
**
** The default way of implementing this query is to execute the
** subquery first and store the results in a temporary table, then
** run the outer query on that temporary table. This requires two
** passes over the data. Furthermore, because the temporary table
** has no indices, the WHERE clause on the outer query cannot be
** optimized.
**
** This routine attempts to rewrite queries such as the above into
** a single flat select, like this:
**
** SELECT x+y AS a FROM t1 WHERE z<100 AND a>5
**
** The code generated for this simplification gives the same result
** but only has to scan the data once. And because indices might
** exist on the table t1, a complete scan of the data might be
** avoided.
**
** Flattening is subject to the following constraints:
**
** (**) We no longer attempt to flatten aggregate subqueries. Was:
** The subquery and the outer query cannot both be aggregates.
**
** (**) We no longer attempt to flatten aggregate subqueries. Was:
** (2) If the subquery is an aggregate then
** (2a) the outer query must not be a join and
** (2b) the outer query must not use subqueries
** other than the one FROM-clause subquery that is a candidate
** for flattening. (This is due to ticket [2f7170d73bf9abf80]
** from 2015-02-09.)
**
** (3) If the subquery is the right operand of a LEFT JOIN then
** (3a) the subquery may not be a join and
** (3b) the FROM clause of the subquery may not contain a virtual
** table and
** (3c) the outer query may not be an aggregate.
**
** (4) The subquery can not be DISTINCT.
**
** (**) At one point restrictions (4) and (5) defined a subset of DISTINCT
** sub-queries that were excluded from this optimization. Restriction
** (4) has since been expanded to exclude all DISTINCT subqueries.
**
** (**) We no longer attempt to flatten aggregate subqueries. Was:
** If the subquery is aggregate, the outer query may not be DISTINCT.
**
** (7) The subquery must have a FROM clause. TODO: For subqueries without
** A FROM clause, consider adding a FROM clause with the special
** table sqlite_once that consists of a single row containing a
** single NULL.
**
** (8) If the subquery uses LIMIT then the outer query may not be a join.
**
** (9) If the subquery uses LIMIT then the outer query may not be aggregate.
**
** (**) Restriction (10) was removed from the code on 2005-02-05 but we
** accidently carried the comment forward until 2014-09-15. Original
** constraint: "If the subquery is aggregate then the outer query
** may not use LIMIT."
**
** (11) The subquery and the outer query may not both have ORDER BY clauses.
**
** (**) Not implemented. Subsumed into restriction (3). Was previously
** a separate restriction deriving from ticket #350.
**
** (13) The subquery and outer query may not both use LIMIT.
**
** (14) The subquery may not use OFFSET.
**
** (15) If the outer query is part of a compound select, then the
** subquery may not use LIMIT.
** (See ticket #2339 and ticket [02a8e81d44]).
**
** (16) If the outer query is aggregate, then the subquery may not
** use ORDER BY. (Ticket #2942) This used to not matter
** until we introduced the group_concat() function.
**
** (17) If the subquery is a compound select, then
** (17a) all compound operators must be a UNION ALL, and
** (17b) no terms within the subquery compound may be aggregate
** or DISTINCT, and
** (17c) every term within the subquery compound must have a FROM clause
** (17d) the outer query may not be
** (17d1) aggregate, or
** (17d2) DISTINCT, or
** (17d3) a join.
**
** The parent and sub-query may contain WHERE clauses. Subject to
** rules (11), (13) and (14), they may also contain ORDER BY,
** LIMIT and OFFSET clauses. The subquery cannot use any compound
** operator other than UNION ALL because all the other compound
** operators have an implied DISTINCT which is disallowed by
** restriction (4).
**
** Also, each component of the sub-query must return the same number
** of result columns. This is actually a requirement for any compound
** SELECT statement, but all the code here does is make sure that no
** such (illegal) sub-query is flattened. The caller will detect the
** syntax error and return a detailed message.
**
** (18) If the sub-query is a compound select, then all terms of the
** ORDER BY clause of the parent must be simple references to
** columns of the sub-query.
**
** (19) If the subquery uses LIMIT then the outer query may not
** have a WHERE clause.
**
** (20) If the sub-query is a compound select, then it must not use
** an ORDER BY clause. Ticket #3773. We could relax this constraint
** somewhat by saying that the terms of the ORDER BY clause must
** appear as unmodified result columns in the outer query. But we
** have other optimizations in mind to deal with that case.
**
** (21) If the subquery uses LIMIT then the outer query may not be
** DISTINCT. (See ticket [752e1646fc]).
**
** (22) The subquery may not be a recursive CTE.
**
** (**) Subsumed into restriction (17d3). Was: If the outer query is
** a recursive CTE, then the sub-query may not be a compound query.
** This restriction is because transforming the
** parent to a compound query confuses the code that handles
** recursive queries in multiSelect().
**
** (**) We no longer attempt to flatten aggregate subqueries. Was:
** The subquery may not be an aggregate that uses the built-in min() or
** or max() functions. (Without this restriction, a query like:
** "SELECT x FROM (SELECT max(y), x FROM t1)" would not necessarily
** return the value X for which Y was maximal.)
**
**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query
** uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and returns 0.
** If flattening is attempted this routine returns 1.
**
** All of the expression analysis must occur on both the outer query and
** the subquery before this routine runs.
*/
static int flattenSubquery(
Parse *pParse, /* Parsing context */
Select *p, /* The parent or outer SELECT statement */
int iFrom, /* Index in p->pSrc->a[] of the inner subquery */
int isAgg /* True if outer SELECT uses aggregate functions */
){
const char *zSavedAuthContext = pParse->zAuthContext;
Select *pParent; /* Current UNION ALL term of the other query */
Select *pSub; /* The inner query or "subquery" */
Select *pSub1; /* Pointer to the rightmost select in sub-query */
SrcList *pSrc; /* The FROM clause of the outer query */
SrcList *pSubSrc; /* The FROM clause of the subquery */
int iParent; /* VDBE cursor number of the pSub result set temp table */
int iNewParent = -1;/* Replacement table for iParent */
int isLeftJoin = 0; /* True if pSub is the right side of a LEFT JOIN */
int i; /* Loop counter */
Expr *pWhere; /* The WHERE clause */
struct SrcList_item *pSubitem; /* The subquery */
sqlite3 *db = pParse->db;
/* Check to see if flattening is permitted. Return 0 if not.
*/
assert( p!=0 );
assert( p->pPrior==0 );
if( OptimizationDisabled(db, SQLITE_QueryFlattener) ) return 0;
pSrc = p->pSrc;
assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
pSubitem = &pSrc->a[iFrom];
iParent = pSubitem->iCursor;
pSub = pSubitem->pSelect;
assert( pSub!=0 );
pSubSrc = pSub->pSrc;
assert( pSubSrc );
/* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
** not arbitrary expressions, we allowed some combining of LIMIT and OFFSET
** because they could be computed at compile-time. But when LIMIT and OFFSET
** became arbitrary expressions, we were forced to add restrictions (13)
** and (14). */
if( pSub->pLimit && p->pLimit ) return 0; /* Restriction (13) */
if( pSub->pLimit && pSub->pLimit->pRight ) return 0; /* Restriction (14) */
if( (p->selFlags & SF_Compound)!=0 && pSub->pLimit ){
return 0; /* Restriction (15) */
}
if( pSubSrc->nSrc==0 ) return 0; /* Restriction (7) */
if( pSub->selFlags & SF_Distinct ) return 0; /* Restriction (4) */
if( pSub->pLimit && (pSrc->nSrc>1 || isAgg) ){
return 0; /* Restrictions (8)(9) */
}
if( p->pOrderBy && pSub->pOrderBy ){
return 0; /* Restriction (11) */
}
if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */
if( pSub->pLimit && p->pWhere ) return 0; /* Restriction (19) */
if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){
return 0; /* Restriction (21) */
}
if( pSub->selFlags & (SF_Recursive) ){
return 0; /* Restrictions (22) */
}
/*
** If the subquery is the right operand of a LEFT JOIN, then the
** subquery may not be a join itself (3a). Example of why this is not
** allowed:
**
** t1 LEFT OUTER JOIN (t2 JOIN t3)
**
** If we flatten the above, we would get
**
** (t1 LEFT OUTER JOIN t2) JOIN t3
**
** which is not at all the same thing.
**
** If the subquery is the right operand of a LEFT JOIN, then the outer
** query cannot be an aggregate. (3c) This is an artifact of the way
** aggregates are processed - there is no mechanism to determine if
** the LEFT JOIN table should be all-NULL.
**
** See also tickets #306, #350, and #3300.
*/
if( (pSubitem->fg.jointype & JT_OUTER)!=0 ){
isLeftJoin = 1;
if( pSubSrc->nSrc>1 || isAgg || IsVirtual(pSubSrc->a[0].pTab) ){
/* (3a) (3c) (3b) */
return 0;
}
}
#ifdef SQLITE_EXTRA_IFNULLROW
else if( iFrom>0 && !isAgg ){
/* Setting isLeftJoin to -1 causes OP_IfNullRow opcodes to be generated for
** every reference to any result column from subquery in a join, even
** though they are not necessary. This will stress-test the OP_IfNullRow
** opcode. */
isLeftJoin = -1;
}
#endif
/* Restriction (17): If the sub-query is a compound SELECT, then it must
** use only the UNION ALL operator. And none of the simple select queries
** that make up the compound SELECT are allowed to be aggregate or distinct
** queries.
*/
if( pSub->pPrior ){
if( pSub->pOrderBy ){
return 0; /* Restriction (20) */
}
if( isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){
return 0; /* (17d1), (17d2), or (17d3) */
}
for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
assert( pSub->pSrc!=0 );
assert( pSub->pEList->nExpr==pSub1->pEList->nExpr );
if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0 /* (17b) */
|| (pSub1->pPrior && pSub1->op!=TK_ALL) /* (17a) */
|| pSub1->pSrc->nSrc<1 /* (17c) */
){
return 0;
}
testcase( pSub1->pSrc->nSrc>1 );
}
/* Restriction (18). */
if( p->pOrderBy ){
int ii;
for(ii=0; ii<p->pOrderBy->nExpr; ii++){
if( p->pOrderBy->a[ii].u.x.iOrderByCol==0 ) return 0;
}
}
}
/* Ex-restriction (23):
** The only way that the recursive part of a CTE can contain a compound
** subquery is for the subquery to be one term of a join. But if the
** subquery is a join, then the flattening has already been stopped by
** restriction (17d3)
*/
assert( (p->selFlags & SF_Recursive)==0 || pSub->pPrior==0 );
/***** If we reach this point, flattening is permitted. *****/
SELECTTRACE(1,pParse,p,("flatten %s.%p from term %d\n",
pSub->zSelName, pSub, iFrom));
/* Authorize the subquery */
pParse->zAuthContext = pSubitem->zName;
TESTONLY(i =) sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0);
testcase( i==SQLITE_DENY );
pParse->zAuthContext = zSavedAuthContext;
/* If the sub-query is a compound SELECT statement, then (by restrictions
** 17 and 18 above) it must be a UNION ALL and the parent query must
** be of the form:
**
** SELECT <expr-list> FROM (<sub-query>) <where-clause>
**
** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block
** creates N-1 copies of the parent query without any ORDER BY, LIMIT or
** OFFSET clauses and joins them to the left-hand-side of the original
** using UNION ALL operators. In this case N is the number of simple
** select statements in the compound sub-query.
**
** Example:
**
** SELECT a+1 FROM (
** SELECT x FROM tab
** UNION ALL
** SELECT y FROM tab
** UNION ALL
** SELECT abs(z*2) FROM tab2
** ) WHERE a!=5 ORDER BY 1
**
** Transformed into:
**
** SELECT x+1 FROM tab WHERE x+1!=5
** UNION ALL
** SELECT y+1 FROM tab WHERE y+1!=5
** UNION ALL
** SELECT abs(z*2)+1 FROM tab2 WHERE abs(z*2)+1!=5
** ORDER BY 1
**
** We call this the "compound-subquery flattening".
*/
for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){
Select *pNew;
ExprList *pOrderBy = p->pOrderBy;
Expr *pLimit = p->pLimit;
Select *pPrior = p->pPrior;
p->pOrderBy = 0;
p->pSrc = 0;
p->pPrior = 0;
p->pLimit = 0;
pNew = sqlite3SelectDup(db, p, 0);
sqlite3SelectSetName(pNew, pSub->zSelName);
p->pLimit = pLimit;
p->pOrderBy = pOrderBy;
p->pSrc = pSrc;
p->op = TK_ALL;
if( pNew==0 ){
p->pPrior = pPrior;
}else{
pNew->pPrior = pPrior;
if( pPrior ) pPrior->pNext = pNew;
pNew->pNext = p;
p->pPrior = pNew;
SELECTTRACE(2,pParse,p,("compound-subquery flattener"
" creates %s.%p as peer\n",pNew->zSelName, pNew));
}
if( db->mallocFailed ) return 1;
}
/* Begin flattening the iFrom-th entry of the FROM clause
** in the outer query.
*/
pSub = pSub1 = pSubitem->pSelect;
/* Delete the transient table structure associated with the
** subquery
*/
sqlite3DbFree(db, pSubitem->zDatabase);
sqlite3DbFree(db, pSubitem->zName);
sqlite3DbFree(db, pSubitem->zAlias);
pSubitem->zDatabase = 0;
pSubitem->zName = 0;
pSubitem->zAlias = 0;
pSubitem->pSelect = 0;
/* Defer deleting the Table object associated with the
** subquery until code generation is
** complete, since there may still exist Expr.pTab entries that
** refer to the subquery even after flattening. Ticket #3346.
**
** pSubitem->pTab is always non-NULL by test restrictions and tests above.
*/
if( ALWAYS(pSubitem->pTab!=0) ){
Table *pTabToDel = pSubitem->pTab;
if( pTabToDel->nTabRef==1 ){
Parse *pToplevel = sqlite3ParseToplevel(pParse);
pTabToDel->pNextZombie = pToplevel->pZombieTab;
pToplevel->pZombieTab = pTabToDel;
}else{
pTabToDel->nTabRef--;
}
pSubitem->pTab = 0;
}
/* The following loop runs once for each term in a compound-subquery
** flattening (as described above). If we are doing a different kind
** of flattening - a flattening other than a compound-subquery flattening -
** then this loop only runs once.
**
** This loop moves all of the FROM elements of the subquery into the
** the FROM clause of the outer query. Before doing this, remember
** the cursor number for the original outer query FROM element in
** iParent. The iParent cursor will never be used. Subsequent code
** will scan expressions looking for iParent references and replace
** those references with expressions that resolve to the subquery FROM
** elements we are now copying in.
*/
for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){
int nSubSrc;
u8 jointype = 0;
pSubSrc = pSub->pSrc; /* FROM clause of subquery */
nSubSrc = pSubSrc->nSrc; /* Number of terms in subquery FROM clause */
pSrc = pParent->pSrc; /* FROM clause of the outer query */
if( pSrc ){
assert( pParent==p ); /* First time through the loop */
jointype = pSubitem->fg.jointype;
}else{
assert( pParent!=p ); /* 2nd and subsequent times through the loop */
pSrc = pParent->pSrc = sqlite3SrcListAppend(db, 0, 0, 0);
if( pSrc==0 ){
assert( db->mallocFailed );
break;
}
}
/* The subquery uses a single slot of the FROM clause of the outer
** query. If the subquery has more than one element in its FROM clause,
** then expand the outer query to make space for it to hold all elements
** of the subquery.
**
** Example:
**
** SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB;
**
** The outer query has 3 slots in its FROM clause. One slot of the
** outer query (the middle slot) is used by the subquery. The next
** block of code will expand the outer query FROM clause to 4 slots.
** The middle slot is expanded to two slots in order to make space
** for the two elements in the FROM clause of the subquery.
*/
if( nSubSrc>1 ){
pParent->pSrc = pSrc = sqlite3SrcListEnlarge(db, pSrc, nSubSrc-1,iFrom+1);
if( db->mallocFailed ){
break;
}
}
/* Transfer the FROM clause terms from the subquery into the
** outer query.
*/
for(i=0; i<nSubSrc; i++){
sqlite3IdListDelete(db, pSrc->a[i+iFrom].pUsing);
assert( pSrc->a[i+iFrom].fg.isTabFunc==0 );
pSrc->a[i+iFrom] = pSubSrc->a[i];
iNewParent = pSubSrc->a[i].iCursor;
memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
}
pSrc->a[iFrom].fg.jointype = jointype;
/* Now begin substituting subquery result set expressions for
** references to the iParent in the outer query.
**
** Example:
**
** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
** \ \_____________ subquery __________/ /
** \_____________________ outer query ______________________________/
**
** We look at every expression in the outer query and every place we see
** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
*/
if( pSub->pOrderBy ){
/* At this point, any non-zero iOrderByCol values indicate that the
** ORDER BY column expression is identical to the iOrderByCol'th
** expression returned by SELECT statement pSub. Since these values
** do not necessarily correspond to columns in SELECT statement pParent,
** zero them before transfering the ORDER BY clause.
**
** Not doing this may cause an error if a subsequent call to this
** function attempts to flatten a compound sub-query into pParent
** (the only way this can happen is if the compound sub-query is
** currently part of pSub->pSrc). See ticket [d11a6e908f]. */
ExprList *pOrderBy = pSub->pOrderBy;
for(i=0; i<pOrderBy->nExpr; i++){
pOrderBy->a[i].u.x.iOrderByCol = 0;
}
assert( pParent->pOrderBy==0 );
pParent->pOrderBy = pOrderBy;
pSub->pOrderBy = 0;
}
pWhere = sqlite3ExprDup(db, pSub->pWhere, 0);
if( isLeftJoin>0 ){
setJoinExpr(pWhere, iNewParent);
}
pParent->pWhere = sqlite3ExprAnd(db, pWhere, pParent->pWhere);
if( db->mallocFailed==0 ){
SubstContext x;
x.pParse = pParse;
x.iTable = iParent;
x.iNewTable = iNewParent;
x.isLeftJoin = isLeftJoin;
x.pEList = pSub->pEList;
substSelect(&x, pParent, 0);
}
/* The flattened query is distinct if either the inner or the
** outer query is distinct.
*/
pParent->selFlags |= pSub->selFlags & SF_Distinct;
/*
** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
**
** One is tempted to try to add a and b to combine the limits. But this
** does not work if either limit is negative.
*/
if( pSub->pLimit ){
pParent->pLimit = pSub->pLimit;
pSub->pLimit = 0;
}
}
/* Finially, delete what is left of the subquery and return
** success.
*/
sqlite3SelectDelete(db, pSub1);
#if SELECTTRACE_ENABLED
if( sqlite3SelectTrace & 0x100 ){
SELECTTRACE(0x100,pParse,p,("After flattening:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
return 1;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** Make copies of relevant WHERE clause terms of the outer query into
** the WHERE clause of subquery. Example:
**
** SELECT * FROM (SELECT a AS x, c-d AS y FROM t1) WHERE x=5 AND y=10;
**
** Transformed into:
**
** SELECT * FROM (SELECT a AS x, c-d AS y FROM t1 WHERE a=5 AND c-d=10)
** WHERE x=5 AND y=10;
**
** The hope is that the terms added to the inner query will make it more
** efficient.
**
** Do not attempt this optimization if:
**
** (1) (** This restriction was removed on 2017-09-29. We used to
** disallow this optimization for aggregate subqueries, but now
** it is allowed by putting the extra terms on the HAVING clause.
** The added HAVING clause is pointless if the subquery lacks
** a GROUP BY clause. But such a HAVING clause is also harmless
** so there does not appear to be any reason to add extra logic
** to suppress it. **)
**
** (2) The inner query is the recursive part of a common table expression.
**
** (3) The inner query has a LIMIT clause (since the changes to the WHERE
** close would change the meaning of the LIMIT).
**
** (4) The inner query is the right operand of a LEFT JOIN and the
** expression to be pushed down does not come from the ON clause
** on that LEFT JOIN.
**
** (5) The WHERE clause expression originates in the ON or USING clause
** of a LEFT JOIN where iCursor is not the right-hand table of that
** left join. An example:
**
** SELECT *
** FROM (SELECT 1 AS a1 UNION ALL SELECT 2) AS aa
** JOIN (SELECT 1 AS b2 UNION ALL SELECT 2) AS bb ON (a1=b2)
** LEFT JOIN (SELECT 8 AS c3 UNION ALL SELECT 9) AS cc ON (b2=2);
**
** The correct answer is three rows: (1,1,NULL),(2,2,8),(2,2,9).
** But if the (b2=2) term were to be pushed down into the bb subquery,
** then the (1,1,NULL) row would be suppressed.
**
** Return 0 if no changes are made and non-zero if one or more WHERE clause
** terms are duplicated into the subquery.
*/
static int pushDownWhereTerms(
Parse *pParse, /* Parse context (for malloc() and error reporting) */
Select *pSubq, /* The subquery whose WHERE clause is to be augmented */
Expr *pWhere, /* The WHERE clause of the outer query */
int iCursor, /* Cursor number of the subquery */
int isLeftJoin /* True if pSubq is the right term of a LEFT JOIN */
){
Expr *pNew;
int nChng = 0;
if( pWhere==0 ) return 0;
if( pSubq->selFlags & SF_Recursive ) return 0; /* restriction (2) */
#ifdef SQLITE_DEBUG
/* Only the first term of a compound can have a WITH clause. But make
** sure no other terms are marked SF_Recursive in case something changes
** in the future.
*/
{
Select *pX;
for(pX=pSubq; pX; pX=pX->pPrior){
assert( (pX->selFlags & (SF_Recursive))==0 );
}
}
#endif
if( pSubq->pLimit!=0 ){
return 0; /* restriction (3) */
}
while( pWhere->op==TK_AND ){
nChng += pushDownWhereTerms(pParse, pSubq, pWhere->pRight,
iCursor, isLeftJoin);
pWhere = pWhere->pLeft;
}
if( isLeftJoin
&& (ExprHasProperty(pWhere,EP_FromJoin)==0
|| pWhere->iRightJoinTable!=iCursor)
){
return 0; /* restriction (4) */
}
if( ExprHasProperty(pWhere,EP_FromJoin) && pWhere->iRightJoinTable!=iCursor ){
return 0; /* restriction (5) */
}
if( sqlite3ExprIsTableConstant(pWhere, iCursor) ){
nChng++;
while( pSubq ){
SubstContext x;
pNew = sqlite3ExprDup(pParse->db, pWhere, 0);
unsetJoinExpr(pNew, -1);
x.pParse = pParse;
x.iTable = iCursor;
x.iNewTable = iCursor;
x.isLeftJoin = 0;
x.pEList = pSubq->pEList;
pNew = substExpr(&x, pNew);
if( pSubq->selFlags & SF_Aggregate ){
pSubq->pHaving = sqlite3ExprAnd(pParse->db, pSubq->pHaving, pNew);
}else{
pSubq->pWhere = sqlite3ExprAnd(pParse->db, pSubq->pWhere, pNew);
}
pSubq = pSubq->pPrior;
}
}
return nChng;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
/*
** The pFunc is the only aggregate function in the query. Check to see
** if the query is a candidate for the min/max optimization.
**
** If the query is a candidate for the min/max optimization, then set
** *ppMinMax to be an ORDER BY clause to be used for the optimization
** and return either WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX depending on
** whether pFunc is a min() or max() function.
**
** If the query is not a candidate for the min/max optimization, return
** WHERE_ORDERBY_NORMAL (which must be zero).
**
** This routine must be called after aggregate functions have been
** located but before their arguments have been subjected to aggregate
** analysis.
*/
static u8 minMaxQuery(sqlite3 *db, Expr *pFunc, ExprList **ppMinMax){
int eRet = WHERE_ORDERBY_NORMAL; /* Return value */
ExprList *pEList = pFunc->x.pList; /* Arguments to agg function */
const char *zFunc; /* Name of aggregate function pFunc */
ExprList *pOrderBy;
u8 sortOrder;
assert( *ppMinMax==0 );
assert( pFunc->op==TK_AGG_FUNCTION );
if( pEList==0 || pEList->nExpr!=1 ) return eRet;
zFunc = pFunc->u.zToken;
if( sqlite3StrICmp(zFunc, "min")==0 ){
eRet = WHERE_ORDERBY_MIN;
sortOrder = SQLITE_SO_ASC;
}else if( sqlite3StrICmp(zFunc, "max")==0 ){
eRet = WHERE_ORDERBY_MAX;
sortOrder = SQLITE_SO_DESC;
}else{
return eRet;
}
*ppMinMax = pOrderBy = sqlite3ExprListDup(db, pEList, 0);
assert( pOrderBy!=0 || db->mallocFailed );
if( pOrderBy ) pOrderBy->a[0].sortOrder = sortOrder;
return eRet;
}
/*
** The select statement passed as the first argument is an aggregate query.
** The second argument is the associated aggregate-info object. This
** function tests if the SELECT is of the form:
**
** SELECT count(*) FROM <tbl>
**
** where table is a database table, not a sub-select or view. If the query
** does match this pattern, then a pointer to the Table object representing
** <tbl> is returned. Otherwise, 0 is returned.
*/
static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){
Table *pTab;
Expr *pExpr;
assert( !p->pGroupBy );
if( p->pWhere || p->pEList->nExpr!=1
|| p->pSrc->nSrc!=1 || p->pSrc->a[0].pSelect
){
return 0;
}
pTab = p->pSrc->a[0].pTab;
pExpr = p->pEList->a[0].pExpr;
assert( pTab && !pTab->pSelect && pExpr );
if( IsVirtual(pTab) ) return 0;
if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
if( NEVER(pAggInfo->nFunc==0) ) return 0;
if( (pAggInfo->aFunc[0].pFunc->funcFlags&SQLITE_FUNC_COUNT)==0 ) return 0;
if( pExpr->flags&EP_Distinct ) return 0;
return pTab;
}
/*
** If the source-list item passed as an argument was augmented with an
** INDEXED BY clause, then try to locate the specified index. If there
** was such a clause and the named index cannot be found, return
** SQLITE_ERROR and leave an error in pParse. Otherwise, populate
** pFrom->pIndex and return SQLITE_OK.
*/
int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){
if( pFrom->pTab && pFrom->fg.isIndexedBy ){
Table *pTab = pFrom->pTab;
char *zIndexedBy = pFrom->u1.zIndexedBy;
Index *pIdx;
for(pIdx=pTab->pIndex;
pIdx && sqlite3StrICmp(pIdx->zName, zIndexedBy);
pIdx=pIdx->pNext
);
if( !pIdx ){
sqlite3ErrorMsg(pParse, "no such index: %s", zIndexedBy, 0);
pParse->checkSchema = 1;
return SQLITE_ERROR;
}
pFrom->pIBIndex = pIdx;
}
return SQLITE_OK;
}
/*
** Detect compound SELECT statements that use an ORDER BY clause with
** an alternative collating sequence.
**
** SELECT ... FROM t1 EXCEPT SELECT ... FROM t2 ORDER BY .. COLLATE ...
**
** These are rewritten as a subquery:
**
** SELECT * FROM (SELECT ... FROM t1 EXCEPT SELECT ... FROM t2)
** ORDER BY ... COLLATE ...
**
** This transformation is necessary because the multiSelectOrderBy() routine
** above that generates the code for a compound SELECT with an ORDER BY clause
** uses a merge algorithm that requires the same collating sequence on the
** result columns as on the ORDER BY clause. See ticket
** http://www.sqlite.org/src/info/6709574d2a
**
** This transformation is only needed for EXCEPT, INTERSECT, and UNION.
** The UNION ALL operator works fine with multiSelectOrderBy() even when
** there are COLLATE terms in the ORDER BY.
*/
static int convertCompoundSelectToSubquery(Walker *pWalker, Select *p){
int i;
Select *pNew;
Select *pX;
sqlite3 *db;
struct ExprList_item *a;
SrcList *pNewSrc;
Parse *pParse;
Token dummy;
if( p->pPrior==0 ) return WRC_Continue;
if( p->pOrderBy==0 ) return WRC_Continue;
for(pX=p; pX && (pX->op==TK_ALL || pX->op==TK_SELECT); pX=pX->pPrior){}
if( pX==0 ) return WRC_Continue;
a = p->pOrderBy->a;
for(i=p->pOrderBy->nExpr-1; i>=0; i--){
if( a[i].pExpr->flags & EP_Collate ) break;
}
if( i<0 ) return WRC_Continue;
/* If we reach this point, that means the transformation is required. */
pParse = pWalker->pParse;
db = pParse->db;
pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
if( pNew==0 ) return WRC_Abort;
memset(&dummy, 0, sizeof(dummy));
pNewSrc = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&dummy,pNew,0,0);
if( pNewSrc==0 ) return WRC_Abort;
*pNew = *p;
p->pSrc = pNewSrc;
p->pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ASTERISK, 0));
p->op = TK_SELECT;
p->pWhere = 0;
pNew->pGroupBy = 0;
pNew->pHaving = 0;
pNew->pOrderBy = 0;
p->pPrior = 0;
p->pNext = 0;
p->pWith = 0;
p->selFlags &= ~SF_Compound;
assert( (p->selFlags & SF_Converted)==0 );
p->selFlags |= SF_Converted;
assert( pNew->pPrior!=0 );
pNew->pPrior->pNext = pNew;
pNew->pLimit = 0;
return WRC_Continue;
}
/*
** Check to see if the FROM clause term pFrom has table-valued function
** arguments. If it does, leave an error message in pParse and return
** non-zero, since pFrom is not allowed to be a table-valued function.
*/
static int cannotBeFunction(Parse *pParse, struct SrcList_item *pFrom){
if( pFrom->fg.isTabFunc ){
sqlite3ErrorMsg(pParse, "'%s' is not a function", pFrom->zName);
return 1;
}
return 0;
}
#ifndef SQLITE_OMIT_CTE
/*
** Argument pWith (which may be NULL) points to a linked list of nested
** WITH contexts, from inner to outermost. If the table identified by
** FROM clause element pItem is really a common-table-expression (CTE)
** then return a pointer to the CTE definition for that table. Otherwise
** return NULL.
**
** If a non-NULL value is returned, set *ppContext to point to the With
** object that the returned CTE belongs to.
*/
static struct Cte *searchWith(
With *pWith, /* Current innermost WITH clause */
struct SrcList_item *pItem, /* FROM clause element to resolve */
With **ppContext /* OUT: WITH clause return value belongs to */
){
const char *zName;
if( pItem->zDatabase==0 && (zName = pItem->zName)!=0 ){
With *p;
for(p=pWith; p; p=p->pOuter){
int i;
for(i=0; i<p->nCte; i++){
if( sqlite3StrICmp(zName, p->a[i].zName)==0 ){
*ppContext = p;
return &p->a[i];
}
}
}
}
return 0;
}
/* The code generator maintains a stack of active WITH clauses
** with the inner-most WITH clause being at the top of the stack.
**
** This routine pushes the WITH clause passed as the second argument
** onto the top of the stack. If argument bFree is true, then this
** WITH clause will never be popped from the stack. In this case it
** should be freed along with the Parse object. In other cases, when
** bFree==0, the With object will be freed along with the SELECT
** statement with which it is associated.
*/
void sqlite3WithPush(Parse *pParse, With *pWith, u8 bFree){
assert( bFree==0 || (pParse->pWith==0 && pParse->pWithToFree==0) );
if( pWith ){
assert( pParse->pWith!=pWith );
pWith->pOuter = pParse->pWith;
pParse->pWith = pWith;
if( bFree ) pParse->pWithToFree = pWith;
}
}
/*
** This function checks if argument pFrom refers to a CTE declared by
** a WITH clause on the stack currently maintained by the parser. And,
** if currently processing a CTE expression, if it is a recursive
** reference to the current CTE.
**
** If pFrom falls into either of the two categories above, pFrom->pTab
** and other fields are populated accordingly. The caller should check
** (pFrom->pTab!=0) to determine whether or not a successful match
** was found.
**
** Whether or not a match is found, SQLITE_OK is returned if no error
** occurs. If an error does occur, an error message is stored in the
** parser and some error code other than SQLITE_OK returned.
*/
static int withExpand(
Walker *pWalker,
struct SrcList_item *pFrom
){
Parse *pParse = pWalker->pParse;
sqlite3 *db = pParse->db;
struct Cte *pCte; /* Matched CTE (or NULL if no match) */
With *pWith; /* WITH clause that pCte belongs to */
assert( pFrom->pTab==0 );
pCte = searchWith(pParse->pWith, pFrom, &pWith);
if( pCte ){
Table *pTab;
ExprList *pEList;
Select *pSel;
Select *pLeft; /* Left-most SELECT statement */
int bMayRecursive; /* True if compound joined by UNION [ALL] */
With *pSavedWith; /* Initial value of pParse->pWith */
/* If pCte->zCteErr is non-NULL at this point, then this is an illegal
** recursive reference to CTE pCte. Leave an error in pParse and return
** early. If pCte->zCteErr is NULL, then this is not a recursive reference.
** In this case, proceed. */
if( pCte->zCteErr ){
sqlite3ErrorMsg(pParse, pCte->zCteErr, pCte->zName);
return SQLITE_ERROR;
}
if( cannotBeFunction(pParse, pFrom) ) return SQLITE_ERROR;
assert( pFrom->pTab==0 );
pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
if( pTab==0 ) return WRC_Abort;
pTab->nTabRef = 1;
pTab->zName = sqlite3DbStrDup(db, pCte->zName);
pTab->iPKey = -1;
pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
pTab->tabFlags |= TF_Ephemeral | TF_NoVisibleRowid;
pFrom->pSelect = sqlite3SelectDup(db, pCte->pSelect, 0);
if( db->mallocFailed ) return SQLITE_NOMEM_BKPT;
assert( pFrom->pSelect );
/* Check if this is a recursive CTE. */
pSel = pFrom->pSelect;
bMayRecursive = ( pSel->op==TK_ALL || pSel->op==TK_UNION );
if( bMayRecursive ){
int i;
SrcList *pSrc = pFrom->pSelect->pSrc;
for(i=0; i<pSrc->nSrc; i++){
struct SrcList_item *pItem = &pSrc->a[i];
if( pItem->zDatabase==0
&& pItem->zName!=0
&& 0==sqlite3StrICmp(pItem->zName, pCte->zName)
){
pItem->pTab = pTab;
pItem->fg.isRecursive = 1;
pTab->nTabRef++;
pSel->selFlags |= SF_Recursive;
}
}
}
/* Only one recursive reference is permitted. */
if( pTab->nTabRef>2 ){
sqlite3ErrorMsg(
pParse, "multiple references to recursive table: %s", pCte->zName
);
return SQLITE_ERROR;
}
assert( pTab->nTabRef==1 ||
((pSel->selFlags&SF_Recursive) && pTab->nTabRef==2 ));
pCte->zCteErr = "circular reference: %s";
pSavedWith = pParse->pWith;
pParse->pWith = pWith;
if( bMayRecursive ){
Select *pPrior = pSel->pPrior;
assert( pPrior->pWith==0 );
pPrior->pWith = pSel->pWith;
sqlite3WalkSelect(pWalker, pPrior);
pPrior->pWith = 0;
}else{
sqlite3WalkSelect(pWalker, pSel);
}
pParse->pWith = pWith;
for(pLeft=pSel; pLeft->pPrior; pLeft=pLeft->pPrior);
pEList = pLeft->pEList;
if( pCte->pCols ){
if( pEList && pEList->nExpr!=pCte->pCols->nExpr ){
sqlite3ErrorMsg(pParse, "table %s has %d values for %d columns",
pCte->zName, pEList->nExpr, pCte->pCols->nExpr
);
pParse->pWith = pSavedWith;
return SQLITE_ERROR;
}
pEList = pCte->pCols;
}
sqlite3ColumnsFromExprList(pParse, pEList, &pTab->nCol, &pTab->aCol);
if( bMayRecursive ){
if( pSel->selFlags & SF_Recursive ){
pCte->zCteErr = "multiple recursive references: %s";
}else{
pCte->zCteErr = "recursive reference in a subquery: %s";
}
sqlite3WalkSelect(pWalker, pSel);
}
pCte->zCteErr = 0;
pParse->pWith = pSavedWith;
}
return SQLITE_OK;
}
#endif
#ifndef SQLITE_OMIT_CTE
/*
** If the SELECT passed as the second argument has an associated WITH
** clause, pop it from the stack stored as part of the Parse object.
**
** This function is used as the xSelectCallback2() callback by
** sqlite3SelectExpand() when walking a SELECT tree to resolve table
** names and other FROM clause elements.
*/
static void selectPopWith(Walker *pWalker, Select *p){
Parse *pParse = pWalker->pParse;
if( OK_IF_ALWAYS_TRUE(pParse->pWith) && p->pPrior==0 ){
With *pWith = findRightmost(p)->pWith;
if( pWith!=0 ){
assert( pParse->pWith==pWith );
pParse->pWith = pWith->pOuter;
}
}
}
#else
#define selectPopWith 0
#endif
/*
** This routine is a Walker callback for "expanding" a SELECT statement.
** "Expanding" means to do the following:
**
** (1) Make sure VDBE cursor numbers have been assigned to every
** element of the FROM clause.
**
** (2) Fill in the pTabList->a[].pTab fields in the SrcList that
** defines FROM clause. When views appear in the FROM clause,
** fill pTabList->a[].pSelect with a copy of the SELECT statement
** that implements the view. A copy is made of the view's SELECT
** statement so that we can freely modify or delete that statement
** without worrying about messing up the persistent representation
** of the view.
**
** (3) Add terms to the WHERE clause to accommodate the NATURAL keyword
** on joins and the ON and USING clause of joins.
**
** (4) Scan the list of columns in the result set (pEList) looking
** for instances of the "*" operator or the TABLE.* operator.
** If found, expand each "*" to be every column in every table
** and TABLE.* to be every column in TABLE.
**
*/
static int selectExpander(Walker *pWalker, Select *p){
Parse *pParse = pWalker->pParse;
int i, j, k;
SrcList *pTabList;
ExprList *pEList;
struct SrcList_item *pFrom;
sqlite3 *db = pParse->db;
Expr *pE, *pRight, *pExpr;
u16 selFlags = p->selFlags;
u32 elistFlags = 0;
p->selFlags |= SF_Expanded;
if( db->mallocFailed ){
return WRC_Abort;
}
assert( p->pSrc!=0 );
if( (selFlags & SF_Expanded)!=0 ){
return WRC_Prune;
}
pTabList = p->pSrc;
pEList = p->pEList;
sqlite3WithPush(pParse, p->pWith, 0);
/* Make sure cursor numbers have been assigned to all entries in
** the FROM clause of the SELECT statement.
*/
sqlite3SrcListAssignCursors(pParse, pTabList);
/* Look up every table named in the FROM clause of the select. If
** an entry of the FROM clause is a subquery instead of a table or view,
** then create a transient table structure to describe the subquery.
*/
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab;
assert( pFrom->fg.isRecursive==0 || pFrom->pTab!=0 );
if( pFrom->fg.isRecursive ) continue;
assert( pFrom->pTab==0 );
#ifndef SQLITE_OMIT_CTE
if( withExpand(pWalker, pFrom) ) return WRC_Abort;
if( pFrom->pTab ) {} else
#endif
if( pFrom->zName==0 ){
#ifndef SQLITE_OMIT_SUBQUERY
Select *pSel = pFrom->pSelect;
/* A sub-query in the FROM clause of a SELECT */
assert( pSel!=0 );
assert( pFrom->pTab==0 );
if( sqlite3WalkSelect(pWalker, pSel) ) return WRC_Abort;
pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
if( pTab==0 ) return WRC_Abort;
pTab->nTabRef = 1;
if( pFrom->zAlias ){
pTab->zName = sqlite3DbStrDup(db, pFrom->zAlias);
}else{
pTab->zName = sqlite3MPrintf(db, "subquery_%p", (void*)pTab);
}
while( pSel->pPrior ){ pSel = pSel->pPrior; }
sqlite3ColumnsFromExprList(pParse, pSel->pEList,&pTab->nCol,&pTab->aCol);
pTab->iPKey = -1;
pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
pTab->tabFlags |= TF_Ephemeral;
#endif
}else{
/* An ordinary table or view name in the FROM clause */
assert( pFrom->pTab==0 );
pFrom->pTab = pTab = sqlite3LocateTableItem(pParse, 0, pFrom);
if( pTab==0 ) return WRC_Abort;
if( pTab->nTabRef>=0xffff ){
sqlite3ErrorMsg(pParse, "too many references to \"%s\": max 65535",
pTab->zName);
pFrom->pTab = 0;
return WRC_Abort;
}
pTab->nTabRef++;
if( !IsVirtual(pTab) && cannotBeFunction(pParse, pFrom) ){
return WRC_Abort;
}
#if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE)
if( IsVirtual(pTab) || pTab->pSelect ){
i16 nCol;
if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort;
assert( pFrom->pSelect==0 );
pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect, 0);
sqlite3SelectSetName(pFrom->pSelect, pTab->zName);
nCol = pTab->nCol;
pTab->nCol = -1;
sqlite3WalkSelect(pWalker, pFrom->pSelect);
pTab->nCol = nCol;
}
#endif
}
/* Locate the index named by the INDEXED BY clause, if any. */
if( sqlite3IndexedByLookup(pParse, pFrom) ){
return WRC_Abort;
}
}
/* Process NATURAL keywords, and ON and USING clauses of joins.
*/
if( db->mallocFailed || sqliteProcessJoin(pParse, p) ){
return WRC_Abort;
}
/* For every "*" that occurs in the column list, insert the names of
** all columns in all tables. And for every TABLE.* insert the names
** of all columns in TABLE. The parser inserted a special expression
** with the TK_ASTERISK operator for each "*" that it found in the column
** list. The following code just has to locate the TK_ASTERISK
** expressions and expand each one to the list of all columns in
** all tables.
**
** The first loop just checks to see if there are any "*" operators
** that need expanding.
*/
for(k=0; k<pEList->nExpr; k++){
pE = pEList->a[k].pExpr;
if( pE->op==TK_ASTERISK ) break;
assert( pE->op!=TK_DOT || pE->pRight!=0 );
assert( pE->op!=TK_DOT || (pE->pLeft!=0 && pE->pLeft->op==TK_ID) );
if( pE->op==TK_DOT && pE->pRight->op==TK_ASTERISK ) break;
elistFlags |= pE->flags;
}
if( k<pEList->nExpr ){
/*
** If we get here it means the result set contains one or more "*"
** operators that need to be expanded. Loop through each expression
** in the result set and expand them one by one.
*/
struct ExprList_item *a = pEList->a;
ExprList *pNew = 0;
int flags = pParse->db->flags;
int longNames = (flags & SQLITE_FullColNames)!=0
&& (flags & SQLITE_ShortColNames)==0;
for(k=0; k<pEList->nExpr; k++){
pE = a[k].pExpr;
elistFlags |= pE->flags;
pRight = pE->pRight;
assert( pE->op!=TK_DOT || pRight!=0 );
if( pE->op!=TK_ASTERISK
&& (pE->op!=TK_DOT || pRight->op!=TK_ASTERISK)
){
/* This particular expression does not need to be expanded.
*/
pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr);
if( pNew ){
pNew->a[pNew->nExpr-1].zName = a[k].zName;
pNew->a[pNew->nExpr-1].zSpan = a[k].zSpan;
a[k].zName = 0;
a[k].zSpan = 0;
}
a[k].pExpr = 0;
}else{
/* This expression is a "*" or a "TABLE.*" and needs to be
** expanded. */
int tableSeen = 0; /* Set to 1 when TABLE matches */
char *zTName = 0; /* text of name of TABLE */
if( pE->op==TK_DOT ){
assert( pE->pLeft!=0 );
assert( !ExprHasProperty(pE->pLeft, EP_IntValue) );
zTName = pE->pLeft->u.zToken;
}
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab = pFrom->pTab;
Select *pSub = pFrom->pSelect;
char *zTabName = pFrom->zAlias;
const char *zSchemaName = 0;
int iDb;
if( zTabName==0 ){
zTabName = pTab->zName;
}
if( db->mallocFailed ) break;
if( pSub==0 || (pSub->selFlags & SF_NestedFrom)==0 ){
pSub = 0;
if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){
continue;
}
iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
zSchemaName = iDb>=0 ? db->aDb[iDb].zDbSName : "*";
}
for(j=0; j<pTab->nCol; j++){
char *zName = pTab->aCol[j].zName;
char *zColname; /* The computed column name */
char *zToFree; /* Malloced string that needs to be freed */
Token sColname; /* Computed column name as a token */
assert( zName );
if( zTName && pSub
&& sqlite3MatchSpanName(pSub->pEList->a[j].zSpan, 0, zTName, 0)==0
){
continue;
}
/* If a column is marked as 'hidden', omit it from the expanded
** result-set list unless the SELECT has the SF_IncludeHidden
** bit set.
*/
if( (p->selFlags & SF_IncludeHidden)==0
&& IsHiddenColumn(&pTab->aCol[j])
){
continue;
}
tableSeen = 1;
if( i>0 && zTName==0 ){
if( (pFrom->fg.jointype & JT_NATURAL)!=0
&& tableAndColumnIndex(pTabList, i, zName, 0, 0)
){
/* In a NATURAL join, omit the join columns from the
** table to the right of the join */
continue;
}
if( sqlite3IdListIndex(pFrom->pUsing, zName)>=0 ){
/* In a join with a USING clause, omit columns in the
** using clause from the table on the right. */
continue;
}
}
pRight = sqlite3Expr(db, TK_ID, zName);
zColname = zName;
zToFree = 0;
if( longNames || pTabList->nSrc>1 ){
Expr *pLeft;
pLeft = sqlite3Expr(db, TK_ID, zTabName);
pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight);
if( zSchemaName ){
pLeft = sqlite3Expr(db, TK_ID, zSchemaName);
pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pExpr);
}
if( longNames ){
zColname = sqlite3MPrintf(db, "%s.%s", zTabName, zName);
zToFree = zColname;
}
}else{
pExpr = pRight;
}
pNew = sqlite3ExprListAppend(pParse, pNew, pExpr);
sqlite3TokenInit(&sColname, zColname);
sqlite3ExprListSetName(pParse, pNew, &sColname, 0);
if( pNew && (p->selFlags & SF_NestedFrom)!=0 ){
struct ExprList_item *pX = &pNew->a[pNew->nExpr-1];
if( pSub ){
pX->zSpan = sqlite3DbStrDup(db, pSub->pEList->a[j].zSpan);
testcase( pX->zSpan==0 );
}else{
pX->zSpan = sqlite3MPrintf(db, "%s.%s.%s",
zSchemaName, zTabName, zColname);
testcase( pX->zSpan==0 );
}
pX->bSpanIsTab = 1;
}
sqlite3DbFree(db, zToFree);
}
}
if( !tableSeen ){
if( zTName ){
sqlite3ErrorMsg(pParse, "no such table: %s", zTName);
}else{
sqlite3ErrorMsg(pParse, "no tables specified");
}
}
}
}
sqlite3ExprListDelete(db, pEList);
p->pEList = pNew;
}
if( p->pEList ){
if( p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
sqlite3ErrorMsg(pParse, "too many columns in result set");
return WRC_Abort;
}
if( (elistFlags & (EP_HasFunc|EP_Subquery))!=0 ){
p->selFlags |= SF_ComplexResult;
}
}
return WRC_Continue;
}
/*
** No-op routine for the parse-tree walker.
**
** When this routine is the Walker.xExprCallback then expression trees
** are walked without any actions being taken at each node. Presumably,
** when this routine is used for Walker.xExprCallback then
** Walker.xSelectCallback is set to do something useful for every
** subquery in the parser tree.
*/
int sqlite3ExprWalkNoop(Walker *NotUsed, Expr *NotUsed2){
UNUSED_PARAMETER2(NotUsed, NotUsed2);
return WRC_Continue;
}
/*
** No-op routine for the parse-tree walker for SELECT statements.
** subquery in the parser tree.
*/
int sqlite3SelectWalkNoop(Walker *NotUsed, Select *NotUsed2){
UNUSED_PARAMETER2(NotUsed, NotUsed2);
return WRC_Continue;
}
#if SQLITE_DEBUG
/*
** Always assert. This xSelectCallback2 implementation proves that the
** xSelectCallback2 is never invoked.
*/
void sqlite3SelectWalkAssert2(Walker *NotUsed, Select *NotUsed2){
UNUSED_PARAMETER2(NotUsed, NotUsed2);
assert( 0 );
}
#endif
/*
** This routine "expands" a SELECT statement and all of its subqueries.
** For additional information on what it means to "expand" a SELECT
** statement, see the comment on the selectExpand worker callback above.
**
** Expanding a SELECT statement is the first step in processing a
** SELECT statement. The SELECT statement must be expanded before
** name resolution is performed.
**
** If anything goes wrong, an error message is written into pParse.
** The calling function can detect the problem by looking at pParse->nErr
** and/or pParse->db->mallocFailed.
*/
static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){
Walker w;
w.xExprCallback = sqlite3ExprWalkNoop;
w.pParse = pParse;
if( OK_IF_ALWAYS_TRUE(pParse->hasCompound) ){
w.xSelectCallback = convertCompoundSelectToSubquery;
w.xSelectCallback2 = 0;
sqlite3WalkSelect(&w, pSelect);
}
w.xSelectCallback = selectExpander;
w.xSelectCallback2 = selectPopWith;
sqlite3WalkSelect(&w, pSelect);
}
#ifndef SQLITE_OMIT_SUBQUERY
/*
** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo()
** interface.
**
** For each FROM-clause subquery, add Column.zType and Column.zColl
** information to the Table structure that represents the result set
** of that subquery.
**
** The Table structure that represents the result set was constructed
** by selectExpander() but the type and collation information was omitted
** at that point because identifiers had not yet been resolved. This
** routine is called after identifier resolution.
*/
static void selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){
Parse *pParse;
int i;
SrcList *pTabList;
struct SrcList_item *pFrom;
assert( p->selFlags & SF_Resolved );
assert( (p->selFlags & SF_HasTypeInfo)==0 );
p->selFlags |= SF_HasTypeInfo;
pParse = pWalker->pParse;
pTabList = p->pSrc;
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab = pFrom->pTab;
assert( pTab!=0 );
if( (pTab->tabFlags & TF_Ephemeral)!=0 ){
/* A sub-query in the FROM clause of a SELECT */
Select *pSel = pFrom->pSelect;
if( pSel ){
while( pSel->pPrior ) pSel = pSel->pPrior;
sqlite3SelectAddColumnTypeAndCollation(pParse, pTab, pSel);
}
}
}
}
#endif
/*
** This routine adds datatype and collating sequence information to
** the Table structures of all FROM-clause subqueries in a
** SELECT statement.
**
** Use this routine after name resolution.
*/
static void sqlite3SelectAddTypeInfo(Parse *pParse, Select *pSelect){
#ifndef SQLITE_OMIT_SUBQUERY
Walker w;
w.xSelectCallback = sqlite3SelectWalkNoop;
w.xSelectCallback2 = selectAddSubqueryTypeInfo;
w.xExprCallback = sqlite3ExprWalkNoop;
w.pParse = pParse;
sqlite3WalkSelect(&w, pSelect);
#endif
}
/*
** This routine sets up a SELECT statement for processing. The
** following is accomplished:
**
** * VDBE Cursor numbers are assigned to all FROM-clause terms.
** * Ephemeral Table objects are created for all FROM-clause subqueries.
** * ON and USING clauses are shifted into WHERE statements
** * Wildcards "*" and "TABLE.*" in result sets are expanded.
** * Identifiers in expression are matched to tables.
**
** This routine acts recursively on all subqueries within the SELECT.
*/
void sqlite3SelectPrep(
Parse *pParse, /* The parser context */
Select *p, /* The SELECT statement being coded. */
NameContext *pOuterNC /* Name context for container */
){
assert( p!=0 || pParse->db->mallocFailed );
if( pParse->db->mallocFailed ) return;
if( p->selFlags & SF_HasTypeInfo ) return;
sqlite3SelectExpand(pParse, p);
if( pParse->nErr || pParse->db->mallocFailed ) return;
sqlite3ResolveSelectNames(pParse, p, pOuterNC);
if( pParse->nErr || pParse->db->mallocFailed ) return;
sqlite3SelectAddTypeInfo(pParse, p);
}
/*
** Reset the aggregate accumulator.
**
** The aggregate accumulator is a set of memory cells that hold
** intermediate results while calculating an aggregate. This
** routine generates code that stores NULLs in all of those memory
** cells.
*/
static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
Vdbe *v = pParse->pVdbe;
int i;
struct AggInfo_func *pFunc;
int nReg = pAggInfo->nFunc + pAggInfo->nColumn;
if( nReg==0 ) return;
#ifdef SQLITE_DEBUG
/* Verify that all AggInfo registers are within the range specified by
** AggInfo.mnReg..AggInfo.mxReg */
assert( nReg==pAggInfo->mxReg-pAggInfo->mnReg+1 );
for(i=0; i<pAggInfo->nColumn; i++){
assert( pAggInfo->aCol[i].iMem>=pAggInfo->mnReg
&& pAggInfo->aCol[i].iMem<=pAggInfo->mxReg );
}
for(i=0; i<pAggInfo->nFunc; i++){
assert( pAggInfo->aFunc[i].iMem>=pAggInfo->mnReg
&& pAggInfo->aFunc[i].iMem<=pAggInfo->mxReg );
}
#endif
sqlite3VdbeAddOp3(v, OP_Null, 0, pAggInfo->mnReg, pAggInfo->mxReg);
for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
if( pFunc->iDistinct>=0 ){
Expr *pE = pFunc->pExpr;
assert( !ExprHasProperty(pE, EP_xIsSelect) );
if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){
sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
"argument");
pFunc->iDistinct = -1;
}else{
KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->x.pList, 0, 0);
sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
(char*)pKeyInfo, P4_KEYINFO);
}
}
}
}
/*
** Invoke the OP_AggFinalize opcode for every aggregate function
** in the AggInfo structure.
*/
static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
Vdbe *v = pParse->pVdbe;
int i;
struct AggInfo_func *pF;
for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
ExprList *pList = pF->pExpr->x.pList;
assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) );
sqlite3VdbeAddOp2(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0);
sqlite3VdbeAppendP4(v, pF->pFunc, P4_FUNCDEF);
}
}
/*
** Update the accumulator memory cells for an aggregate based on
** the current cursor position.
*/
static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
Vdbe *v = pParse->pVdbe;
int i;
int regHit = 0;
int addrHitTest = 0;
struct AggInfo_func *pF;
struct AggInfo_col *pC;
pAggInfo->directMode = 1;
for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
int nArg;
int addrNext = 0;
int regAgg;
ExprList *pList = pF->pExpr->x.pList;
assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) );
if( pList ){
nArg = pList->nExpr;
regAgg = sqlite3GetTempRange(pParse, nArg);
sqlite3ExprCodeExprList(pParse, pList, regAgg, 0, SQLITE_ECEL_DUP);
}else{
nArg = 0;
regAgg = 0;
}
if( pF->iDistinct>=0 ){
addrNext = sqlite3VdbeMakeLabel(v);
testcase( nArg==0 ); /* Error condition */
testcase( nArg>1 ); /* Also an error */
codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg);
}
if( pF->pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL ){
CollSeq *pColl = 0;
struct ExprList_item *pItem;
int j;
assert( pList!=0 ); /* pList!=0 if pF->pFunc has NEEDCOLL */
for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){
pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
}
if( !pColl ){
pColl = pParse->db->pDfltColl;
}
if( regHit==0 && pAggInfo->nAccumulator ) regHit = ++pParse->nMem;
sqlite3VdbeAddOp4(v, OP_CollSeq, regHit, 0, 0, (char *)pColl, P4_COLLSEQ);
}
sqlite3VdbeAddOp3(v, OP_AggStep0, 0, regAgg, pF->iMem);
sqlite3VdbeAppendP4(v, pF->pFunc, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, (u8)nArg);
sqlite3ExprCacheAffinityChange(pParse, regAgg, nArg);
sqlite3ReleaseTempRange(pParse, regAgg, nArg);
if( addrNext ){
sqlite3VdbeResolveLabel(v, addrNext);
sqlite3ExprCacheClear(pParse);
}
}
/* Before populating the accumulator registers, clear the column cache.
** Otherwise, if any of the required column values are already present
** in registers, sqlite3ExprCode() may use OP_SCopy to copy the value
** to pC->iMem. But by the time the value is used, the original register
** may have been used, invalidating the underlying buffer holding the
** text or blob value. See ticket [883034dcb5].
**
** Another solution would be to change the OP_SCopy used to copy cached
** values to an OP_Copy.
*/
if( regHit ){
addrHitTest = sqlite3VdbeAddOp1(v, OP_If, regHit); VdbeCoverage(v);
}
sqlite3ExprCacheClear(pParse);
for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
sqlite3ExprCode(pParse, pC->pExpr, pC->iMem);
}
pAggInfo->directMode = 0;
sqlite3ExprCacheClear(pParse);
if( addrHitTest ){
sqlite3VdbeJumpHere(v, addrHitTest);
}
}
/*
** Add a single OP_Explain instruction to the VDBE to explain a simple
** count(*) query ("SELECT count(*) FROM pTab").
*/
#ifndef SQLITE_OMIT_EXPLAIN
static void explainSimpleCount(
Parse *pParse, /* Parse context */
Table *pTab, /* Table being queried */
Index *pIdx /* Index used to optimize scan, or NULL */
){
if( pParse->explain==2 ){
int bCover = (pIdx!=0 && (HasRowid(pTab) || !IsPrimaryKeyIndex(pIdx)));
sqlite3VdbeExplain(pParse, 0, "SCAN TABLE %s%s%s",
pTab->zName,
bCover ? " USING COVERING INDEX " : "",
bCover ? pIdx->zName : ""
);
}
}
#else
# define explainSimpleCount(a,b,c)
#endif
/*
** sqlite3WalkExpr() callback used by havingToWhere().
**
** If the node passed to the callback is a TK_AND node, return
** WRC_Continue to tell sqlite3WalkExpr() to iterate through child nodes.
**
** Otherwise, return WRC_Prune. In this case, also check if the
** sub-expression matches the criteria for being moved to the WHERE
** clause. If so, add it to the WHERE clause and replace the sub-expression
** within the HAVING expression with a constant "1".
*/
static int havingToWhereExprCb(Walker *pWalker, Expr *pExpr){
if( pExpr->op!=TK_AND ){
Select *pS = pWalker->u.pSelect;
if( sqlite3ExprIsConstantOrGroupBy(pWalker->pParse, pExpr, pS->pGroupBy) ){
sqlite3 *db = pWalker->pParse->db;
Expr *pNew = sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[1], 0);
if( pNew ){
Expr *pWhere = pS->pWhere;
SWAP(Expr, *pNew, *pExpr);
pNew = sqlite3ExprAnd(db, pWhere, pNew);
pS->pWhere = pNew;
pWalker->eCode = 1;
}
}
return WRC_Prune;
}
return WRC_Continue;
}
/*
** Transfer eligible terms from the HAVING clause of a query, which is
** processed after grouping, to the WHERE clause, which is processed before
** grouping. For example, the query:
**
** SELECT * FROM <tables> WHERE a=? GROUP BY b HAVING b=? AND c=?
**
** can be rewritten as:
**
** SELECT * FROM <tables> WHERE a=? AND b=? GROUP BY b HAVING c=?
**
** A term of the HAVING expression is eligible for transfer if it consists
** entirely of constants and expressions that are also GROUP BY terms that
** use the "BINARY" collation sequence.
*/
static void havingToWhere(Parse *pParse, Select *p){
Walker sWalker;
memset(&sWalker, 0, sizeof(sWalker));
sWalker.pParse = pParse;
sWalker.xExprCallback = havingToWhereExprCb;
sWalker.u.pSelect = p;
sqlite3WalkExpr(&sWalker, p->pHaving);
#if SELECTTRACE_ENABLED
if( sWalker.eCode && (sqlite3SelectTrace & 0x100)!=0 ){
SELECTTRACE(0x100,pParse,p,("Move HAVING terms into WHERE:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
}
/*
** Check to see if the pThis entry of pTabList is a self-join of a prior view.
** If it is, then return the SrcList_item for the prior view. If it is not,
** then return 0.
*/
static struct SrcList_item *isSelfJoinView(
SrcList *pTabList, /* Search for self-joins in this FROM clause */
struct SrcList_item *pThis /* Search for prior reference to this subquery */
){
struct SrcList_item *pItem;
for(pItem = pTabList->a; pItem<pThis; pItem++){
if( pItem->pSelect==0 ) continue;
if( pItem->fg.viaCoroutine ) continue;
if( pItem->zName==0 ) continue;
if( sqlite3_stricmp(pItem->zDatabase, pThis->zDatabase)!=0 ) continue;
if( sqlite3_stricmp(pItem->zName, pThis->zName)!=0 ) continue;
if( sqlite3ExprCompare(0,
pThis->pSelect->pWhere, pItem->pSelect->pWhere, -1)
){
/* The view was modified by some other optimization such as
** pushDownWhereTerms() */
continue;
}
return pItem;
}
return 0;
}
#ifdef SQLITE_COUNTOFVIEW_OPTIMIZATION
/*
** Attempt to transform a query of the form
**
** SELECT count(*) FROM (SELECT x FROM t1 UNION ALL SELECT y FROM t2)
**
** Into this:
**
** SELECT (SELECT count(*) FROM t1)+(SELECT count(*) FROM t2)
**
** The transformation only works if all of the following are true:
**
** * The subquery is a UNION ALL of two or more terms
** * There is no WHERE or GROUP BY or HAVING clauses on the subqueries
** * The outer query is a simple count(*)
**
** Return TRUE if the optimization is undertaken.
*/
static int countOfViewOptimization(Parse *pParse, Select *p){
Select *pSub, *pPrior;
Expr *pExpr;
Expr *pCount;
sqlite3 *db;
if( (p->selFlags & SF_Aggregate)==0 ) return 0; /* This is an aggregate */
if( p->pEList->nExpr!=1 ) return 0; /* Single result column */
pExpr = p->pEList->a[0].pExpr;
if( pExpr->op!=TK_AGG_FUNCTION ) return 0; /* Result is an aggregate */
if( sqlite3_stricmp(pExpr->u.zToken,"count") ) return 0; /* Is count() */
if( pExpr->x.pList!=0 ) return 0; /* Must be count(*) */
if( p->pSrc->nSrc!=1 ) return 0; /* One table in FROM */
pSub = p->pSrc->a[0].pSelect;
if( pSub==0 ) return 0; /* The FROM is a subquery */
if( pSub->pPrior==0 ) return 0; /* Must be a compound ry */
do{
if( pSub->op!=TK_ALL && pSub->pPrior ) return 0; /* Must be UNION ALL */
if( pSub->pWhere ) return 0; /* No WHERE clause */
if( pSub->selFlags & SF_Aggregate ) return 0; /* Not an aggregate */
pSub = pSub->pPrior; /* Repeat over compound */
}while( pSub );
/* If we reach this point then it is OK to perform the transformation */
db = pParse->db;
pCount = pExpr;
pExpr = 0;
pSub = p->pSrc->a[0].pSelect;
p->pSrc->a[0].pSelect = 0;
sqlite3SrcListDelete(db, p->pSrc);
p->pSrc = sqlite3DbMallocZero(pParse->db, sizeof(*p->pSrc));
while( pSub ){
Expr *pTerm;
pPrior = pSub->pPrior;
pSub->pPrior = 0;
pSub->pNext = 0;
pSub->selFlags |= SF_Aggregate;
pSub->selFlags &= ~SF_Compound;
pSub->nSelectRow = 0;
sqlite3ExprListDelete(db, pSub->pEList);
pTerm = pPrior ? sqlite3ExprDup(db, pCount, 0) : pCount;
pSub->pEList = sqlite3ExprListAppend(pParse, 0, pTerm);
pTerm = sqlite3PExpr(pParse, TK_SELECT, 0, 0);
sqlite3PExprAddSelect(pParse, pTerm, pSub);
if( pExpr==0 ){
pExpr = pTerm;
}else{
pExpr = sqlite3PExpr(pParse, TK_PLUS, pTerm, pExpr);
}
pSub = pPrior;
}
p->pEList->a[0].pExpr = pExpr;
p->selFlags &= ~SF_Aggregate;
#if SELECTTRACE_ENABLED
if( sqlite3SelectTrace & 0x400 ){
SELECTTRACE(0x400,pParse,p,("After count-of-view optimization:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
return 1;
}
#endif /* SQLITE_COUNTOFVIEW_OPTIMIZATION */
/*
** Generate code for the SELECT statement given in the p argument.
**
** The results are returned according to the SelectDest structure.
** See comments in sqliteInt.h for further information.
**
** This routine returns the number of errors. If any errors are
** encountered, then an appropriate error message is left in
** pParse->zErrMsg.
**
** This routine does NOT free the Select structure passed in. The
** calling function needs to do that.
*/
int sqlite3Select(
Parse *pParse, /* The parser context */
Select *p, /* The SELECT statement being coded. */
SelectDest *pDest /* What to do with the query results */
){
int i, j; /* Loop counters */
WhereInfo *pWInfo; /* Return from sqlite3WhereBegin() */
Vdbe *v; /* The virtual machine under construction */
int isAgg; /* True for select lists like "count(*)" */
ExprList *pEList = 0; /* List of columns to extract. */
SrcList *pTabList; /* List of tables to select from */
Expr *pWhere; /* The WHERE clause. May be NULL */
ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */
Expr *pHaving; /* The HAVING clause. May be NULL */
int rc = 1; /* Value to return from this function */
DistinctCtx sDistinct; /* Info on how to code the DISTINCT keyword */
SortCtx sSort; /* Info on how to code the ORDER BY clause */
AggInfo sAggInfo; /* Information used by aggregate queries */
int iEnd; /* Address of the end of the query */
sqlite3 *db; /* The database connection */
ExprList *pMinMaxOrderBy = 0; /* Added ORDER BY for min/max queries */
u8 minMaxFlag; /* Flag for min/max queries */
db = pParse->db;
v = sqlite3GetVdbe(pParse);
if( p==0 || db->mallocFailed || pParse->nErr ){
return 1;
}
if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
memset(&sAggInfo, 0, sizeof(sAggInfo));
#if SELECTTRACE_ENABLED
SELECTTRACE(1,pParse,p, ("begin processing:\n", pParse->addrExplain));
if( sqlite3SelectTrace & 0x100 ){
sqlite3TreeViewSelect(0, p, 0);
}
#endif
assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistFifo );
assert( p->pOrderBy==0 || pDest->eDest!=SRT_Fifo );
assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistQueue );
assert( p->pOrderBy==0 || pDest->eDest!=SRT_Queue );
if( IgnorableOrderby(pDest) ){
assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union ||
pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard ||
pDest->eDest==SRT_Queue || pDest->eDest==SRT_DistFifo ||
pDest->eDest==SRT_DistQueue || pDest->eDest==SRT_Fifo);
/* If ORDER BY makes no difference in the output then neither does
** DISTINCT so it can be removed too. */
sqlite3ExprListDelete(db, p->pOrderBy);
p->pOrderBy = 0;
p->selFlags &= ~SF_Distinct;
}
sqlite3SelectPrep(pParse, p, 0);
memset(&sSort, 0, sizeof(sSort));
sSort.pOrderBy = p->pOrderBy;
pTabList = p->pSrc;
if( pParse->nErr || db->mallocFailed ){
goto select_end;
}
assert( p->pEList!=0 );
isAgg = (p->selFlags & SF_Aggregate)!=0;
#if SELECTTRACE_ENABLED
if( sqlite3SelectTrace & 0x104 ){
SELECTTRACE(0x104,pParse,p, ("after name resolution:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
if( pDest->eDest==SRT_Output ){
generateColumnNames(pParse, p);
}
/* Try to various optimizations (flattening subqueries, and strength
** reduction of join operators) in the FROM clause up into the main query
*/
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
struct SrcList_item *pItem = &pTabList->a[i];
Select *pSub = pItem->pSelect;
Table *pTab = pItem->pTab;
/* Convert LEFT JOIN into JOIN if there are terms of the right table
** of the LEFT JOIN used in the WHERE clause.
*/
if( (pItem->fg.jointype & JT_LEFT)!=0
&& sqlite3ExprImpliesNonNullRow(p->pWhere, pItem->iCursor)
&& OptimizationEnabled(db, SQLITE_SimplifyJoin)
){
SELECTTRACE(0x100,pParse,p,
("LEFT-JOIN simplifies to JOIN on term %d\n",i));
pItem->fg.jointype &= ~(JT_LEFT|JT_OUTER);
unsetJoinExpr(p->pWhere, pItem->iCursor);
}
/* No futher action if this term of the FROM clause is no a subquery */
if( pSub==0 ) continue;
/* Catch mismatch in the declared columns of a view and the number of
** columns in the SELECT on the RHS */
if( pTab->nCol!=pSub->pEList->nExpr ){
sqlite3ErrorMsg(pParse, "expected %d columns for '%s' but got %d",
pTab->nCol, pTab->zName, pSub->pEList->nExpr);
goto select_end;
}
/* Do not try to flatten an aggregate subquery.
**
** Flattening an aggregate subquery is only possible if the outer query
** is not a join. But if the outer query is not a join, then the subquery
** will be implemented as a co-routine and there is no advantage to
** flattening in that case.
*/
if( (pSub->selFlags & SF_Aggregate)!=0 ) continue;
assert( pSub->pGroupBy==0 );
/* If the outer query contains a "complex" result set (that is,
** if the result set of the outer query uses functions or subqueries)
** and if the subquery contains an ORDER BY clause and if
** it will be implemented as a co-routine, then do not flatten. This
** restriction allows SQL constructs like this:
**
** SELECT expensive_function(x)
** FROM (SELECT x FROM tab ORDER BY y LIMIT 10);
**
** The expensive_function() is only computed on the 10 rows that
** are output, rather than every row of the table.
**
** The requirement that the outer query have a complex result set
** means that flattening does occur on simpler SQL constraints without
** the expensive_function() like:
**
** SELECT x FROM (SELECT x FROM tab ORDER BY y LIMIT 10);
*/
if( pSub->pOrderBy!=0
&& i==0
&& (p->selFlags & SF_ComplexResult)!=0
&& (pTabList->nSrc==1
|| (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0)
){
continue;
}
if( flattenSubquery(pParse, p, i, isAgg) ){
/* This subquery can be absorbed into its parent. */
i = -1;
}
pTabList = p->pSrc;
if( db->mallocFailed ) goto select_end;
if( !IgnorableOrderby(pDest) ){
sSort.pOrderBy = p->pOrderBy;
}
}
#endif
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/* Handle compound SELECT statements using the separate multiSelect()
** procedure.
*/
if( p->pPrior ){
rc = multiSelect(pParse, p, pDest);
#if SELECTTRACE_ENABLED
SELECTTRACE(0x1,pParse,p,("end compound-select processing\n"));
if( (sqlite3SelectTrace & 0x2000)!=0 && ExplainQueryPlanParent(pParse)==0 ){
sqlite3TreeViewSelect(0, p, 0);
}
#endif
if( p->pNext==0 ) ExplainQueryPlanPop(pParse);
return rc;
}
#endif
/* For each term in the FROM clause, do two things:
** (1) Authorized unreferenced tables
** (2) Generate code for all sub-queries
*/
for(i=0; i<pTabList->nSrc; i++){
struct SrcList_item *pItem = &pTabList->a[i];
SelectDest dest;
Select *pSub;
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
const char *zSavedAuthContext;
#endif
/* Issue SQLITE_READ authorizations with a fake column name for any
** tables that are referenced but from which no values are extracted.
** Examples of where these kinds of null SQLITE_READ authorizations
** would occur:
**
** SELECT count(*) FROM t1; -- SQLITE_READ t1.""
** SELECT t1.* FROM t1, t2; -- SQLITE_READ t2.""
**
** The fake column name is an empty string. It is possible for a table to
** have a column named by the empty string, in which case there is no way to
** distinguish between an unreferenced table and an actual reference to the
** "" column. The original design was for the fake column name to be a NULL,
** which would be unambiguous. But legacy authorization callbacks might
** assume the column name is non-NULL and segfault. The use of an empty
** string for the fake column name seems safer.
*/
if( pItem->colUsed==0 ){
sqlite3AuthCheck(pParse, SQLITE_READ, pItem->zName, "", pItem->zDatabase);
}
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/* Generate code for all sub-queries in the FROM clause
*/
pSub = pItem->pSelect;
if( pSub==0 ) continue;
/* Sometimes the code for a subquery will be generated more than
** once, if the subquery is part of the WHERE clause in a LEFT JOIN,
** for example. In that case, do not regenerate the code to manifest
** a view or the co-routine to implement a view. The first instance
** is sufficient, though the subroutine to manifest the view does need
** to be invoked again. */
if( pItem->addrFillSub ){
if( pItem->fg.viaCoroutine==0 ){
/* The subroutine that manifests the view might be a one-time routine,
** or it might need to be rerun on each iteration because it
** encodes a correlated subquery. */
testcase( sqlite3VdbeGetOp(v, pItem->addrFillSub)->opcode==OP_Once );
sqlite3VdbeAddOp2(v, OP_Gosub, pItem->regReturn, pItem->addrFillSub);
}
continue;
}
/* Increment Parse.nHeight by the height of the largest expression
** tree referred to by this, the parent select. The child select
** may contain expression trees of at most
** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
** more conservative than necessary, but much easier than enforcing
** an exact limit.
*/
pParse->nHeight += sqlite3SelectExprHeight(p);
/* Make copies of constant WHERE-clause terms in the outer query down
** inside the subquery. This can help the subquery to run more efficiently.
*/
if( OptimizationEnabled(db, SQLITE_PushDown)
&& pushDownWhereTerms(pParse, pSub, p->pWhere, pItem->iCursor,
(pItem->fg.jointype & JT_OUTER)!=0)
){
#if SELECTTRACE_ENABLED
if( sqlite3SelectTrace & 0x100 ){
SELECTTRACE(0x100,pParse,p,("After WHERE-clause push-down:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
}else{
SELECTTRACE(0x100,pParse,p,("Push-down not possible\n"));
}
zSavedAuthContext = pParse->zAuthContext;
pParse->zAuthContext = pItem->zName;
/* Generate code to implement the subquery
**
** The subquery is implemented as a co-routine if the subquery is
** guaranteed to be the outer loop (so that it does not need to be
** computed more than once)
**
** TODO: Are there other reasons beside (1) to use a co-routine
** implementation?
*/
if( i==0
&& (pTabList->nSrc==1
|| (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0) /* (1) */
){
/* Implement a co-routine that will return a single row of the result
** set on each invocation.
*/
int addrTop = sqlite3VdbeCurrentAddr(v)+1;
pItem->regReturn = ++pParse->nMem;
sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
VdbeComment((v, "%s", pItem->pTab->zName));
pItem->addrFillSub = addrTop;
sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
ExplainQueryPlan((pParse, 1, "CO-ROUTINE 0x%p", pSub));
sqlite3Select(pParse, pSub, &dest);
pItem->pTab->nRowLogEst = pSub->nSelectRow;
pItem->fg.viaCoroutine = 1;
pItem->regResult = dest.iSdst;
sqlite3VdbeEndCoroutine(v, pItem->regReturn);
sqlite3VdbeJumpHere(v, addrTop-1);
sqlite3ClearTempRegCache(pParse);
}else{
/* Generate a subroutine that will fill an ephemeral table with
** the content of this subquery. pItem->addrFillSub will point
** to the address of the generated subroutine. pItem->regReturn
** is a register allocated to hold the subroutine return address
*/
int topAddr;
int onceAddr = 0;
int retAddr;
struct SrcList_item *pPrior;
assert( pItem->addrFillSub==0 );
pItem->regReturn = ++pParse->nMem;
topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn);
pItem->addrFillSub = topAddr+1;
if( pItem->fg.isCorrelated==0 ){
/* If the subquery is not correlated and if we are not inside of
** a trigger, then we only need to compute the value of the subquery
** once. */
onceAddr = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
VdbeComment((v, "materialize \"%s\"", pItem->pTab->zName));
}else{
VdbeNoopComment((v, "materialize \"%s\"", pItem->pTab->zName));
}
pPrior = isSelfJoinView(pTabList, pItem);
if( pPrior ){
sqlite3VdbeAddOp2(v, OP_OpenDup, pItem->iCursor, pPrior->iCursor);
assert( pPrior->pSelect!=0 );
pSub->nSelectRow = pPrior->pSelect->nSelectRow;
}else{
sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
ExplainQueryPlan((pParse, 1, "MATERIALIZE 0x%p", pSub));
sqlite3Select(pParse, pSub, &dest);
}
pItem->pTab->nRowLogEst = pSub->nSelectRow;
if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
VdbeComment((v, "end %s", pItem->pTab->zName));
sqlite3VdbeChangeP1(v, topAddr, retAddr);
sqlite3ClearTempRegCache(pParse);
}
if( db->mallocFailed ) goto select_end;
pParse->nHeight -= sqlite3SelectExprHeight(p);
pParse->zAuthContext = zSavedAuthContext;
#endif
}
/* Various elements of the SELECT copied into local variables for
** convenience */
pEList = p->pEList;
pWhere = p->pWhere;
pGroupBy = p->pGroupBy;
pHaving = p->pHaving;
sDistinct.isTnct = (p->selFlags & SF_Distinct)!=0;
#if SELECTTRACE_ENABLED
if( sqlite3SelectTrace & 0x400 ){
SELECTTRACE(0x400,pParse,p,("After all FROM-clause analysis:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
#ifdef SQLITE_COUNTOFVIEW_OPTIMIZATION
if( OptimizationEnabled(db, SQLITE_QueryFlattener|SQLITE_CountOfView)
&& countOfViewOptimization(pParse, p)
){
if( db->mallocFailed ) goto select_end;
pEList = p->pEList;
pTabList = p->pSrc;
}
#endif
/* If the query is DISTINCT with an ORDER BY but is not an aggregate, and
** if the select-list is the same as the ORDER BY list, then this query
** can be rewritten as a GROUP BY. In other words, this:
**
** SELECT DISTINCT xyz FROM ... ORDER BY xyz
**
** is transformed to:
**
** SELECT xyz FROM ... GROUP BY xyz ORDER BY xyz
**
** The second form is preferred as a single index (or temp-table) may be
** used for both the ORDER BY and DISTINCT processing. As originally
** written the query must use a temp-table for at least one of the ORDER
** BY and DISTINCT, and an index or separate temp-table for the other.
*/
if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct
&& sqlite3ExprListCompare(sSort.pOrderBy, pEList, -1)==0
){
p->selFlags &= ~SF_Distinct;
pGroupBy = p->pGroupBy = sqlite3ExprListDup(db, pEList, 0);
/* Notice that even thought SF_Distinct has been cleared from p->selFlags,
** the sDistinct.isTnct is still set. Hence, isTnct represents the
** original setting of the SF_Distinct flag, not the current setting */
assert( sDistinct.isTnct );
#if SELECTTRACE_ENABLED
if( sqlite3SelectTrace & 0x400 ){
SELECTTRACE(0x400,pParse,p,("Transform DISTINCT into GROUP BY:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
}
/* If there is an ORDER BY clause, then create an ephemeral index to
** do the sorting. But this sorting ephemeral index might end up
** being unused if the data can be extracted in pre-sorted order.
** If that is the case, then the OP_OpenEphemeral instruction will be
** changed to an OP_Noop once we figure out that the sorting index is
** not needed. The sSort.addrSortIndex variable is used to facilitate
** that change.
*/
if( sSort.pOrderBy ){
KeyInfo *pKeyInfo;
pKeyInfo = keyInfoFromExprList(pParse, sSort.pOrderBy, 0, pEList->nExpr);
sSort.iECursor = pParse->nTab++;
sSort.addrSortIndex =
sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
sSort.iECursor, sSort.pOrderBy->nExpr+1+pEList->nExpr, 0,
(char*)pKeyInfo, P4_KEYINFO
);
}else{
sSort.addrSortIndex = -1;
}
/* If the output is destined for a temporary table, open that table.
*/
if( pDest->eDest==SRT_EphemTab ){
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iSDParm, pEList->nExpr);
}
/* Set the limiter.
*/
iEnd = sqlite3VdbeMakeLabel(v);
if( (p->selFlags & SF_FixedLimit)==0 ){
p->nSelectRow = 320; /* 4 billion rows */
}
computeLimitRegisters(pParse, p, iEnd);
if( p->iLimit==0 && sSort.addrSortIndex>=0 ){
sqlite3VdbeChangeOpcode(v, sSort.addrSortIndex, OP_SorterOpen);
sSort.sortFlags |= SORTFLAG_UseSorter;
}
/* Open an ephemeral index to use for the distinct set.
*/
if( p->selFlags & SF_Distinct ){
sDistinct.tabTnct = pParse->nTab++;
sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
sDistinct.tabTnct, 0, 0,
(char*)keyInfoFromExprList(pParse, p->pEList,0,0),
P4_KEYINFO);
sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
}else{
sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
}
if( !isAgg && pGroupBy==0 ){
/* No aggregate functions and no GROUP BY clause */
u16 wctrlFlags = (sDistinct.isTnct ? WHERE_WANT_DISTINCT : 0);
assert( WHERE_USE_LIMIT==SF_FixedLimit );
wctrlFlags |= p->selFlags & SF_FixedLimit;
/* Begin the database scan. */
SELECTTRACE(1,pParse,p,("WhereBegin\n"));
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, sSort.pOrderBy,
p->pEList, wctrlFlags, p->nSelectRow);
if( pWInfo==0 ) goto select_end;
if( sqlite3WhereOutputRowCount(pWInfo) < p->nSelectRow ){
p->nSelectRow = sqlite3WhereOutputRowCount(pWInfo);
}
if( sDistinct.isTnct && sqlite3WhereIsDistinct(pWInfo) ){
sDistinct.eTnctType = sqlite3WhereIsDistinct(pWInfo);
}
if( sSort.pOrderBy ){
sSort.nOBSat = sqlite3WhereIsOrdered(pWInfo);
sSort.bOrderedInnerLoop = sqlite3WhereOrderedInnerLoop(pWInfo);
if( sSort.nOBSat==sSort.pOrderBy->nExpr ){
sSort.pOrderBy = 0;
}
}
/* If sorting index that was created by a prior OP_OpenEphemeral
** instruction ended up not being needed, then change the OP_OpenEphemeral
** into an OP_Noop.
*/
if( sSort.addrSortIndex>=0 && sSort.pOrderBy==0 ){
sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex);
}
/* Use the standard inner loop. */
assert( p->pEList==pEList );
selectInnerLoop(pParse, p, -1, &sSort, &sDistinct, pDest,
sqlite3WhereContinueLabel(pWInfo),
sqlite3WhereBreakLabel(pWInfo));
/* End the database scan loop.
*/
sqlite3WhereEnd(pWInfo);
}else{
/* This case when there exist aggregate functions or a GROUP BY clause
** or both */
NameContext sNC; /* Name context for processing aggregate information */
int iAMem; /* First Mem address for storing current GROUP BY */
int iBMem; /* First Mem address for previous GROUP BY */
int iUseFlag; /* Mem address holding flag indicating that at least
** one row of the input to the aggregator has been
** processed */
int iAbortFlag; /* Mem address which causes query abort if positive */
int groupBySort; /* Rows come from source in GROUP BY order */
int addrEnd; /* End of processing for this SELECT */
int sortPTab = 0; /* Pseudotable used to decode sorting results */
int sortOut = 0; /* Output register from the sorter */
int orderByGrp = 0; /* True if the GROUP BY and ORDER BY are the same */
/* Remove any and all aliases between the result set and the
** GROUP BY clause.
*/
if( pGroupBy ){
int k; /* Loop counter */
struct ExprList_item *pItem; /* For looping over expression in a list */
for(k=p->pEList->nExpr, pItem=p->pEList->a; k>0; k--, pItem++){
pItem->u.x.iAlias = 0;
}
for(k=pGroupBy->nExpr, pItem=pGroupBy->a; k>0; k--, pItem++){
pItem->u.x.iAlias = 0;
}
assert( 66==sqlite3LogEst(100) );
if( p->nSelectRow>66 ) p->nSelectRow = 66;
}else{
assert( 0==sqlite3LogEst(1) );
p->nSelectRow = 0;
}
/* If there is both a GROUP BY and an ORDER BY clause and they are
** identical, then it may be possible to disable the ORDER BY clause
** on the grounds that the GROUP BY will cause elements to come out
** in the correct order. It also may not - the GROUP BY might use a
** database index that causes rows to be grouped together as required
** but not actually sorted. Either way, record the fact that the
** ORDER BY and GROUP BY clauses are the same by setting the orderByGrp
** variable. */
if( sqlite3ExprListCompare(pGroupBy, sSort.pOrderBy, -1)==0 ){
orderByGrp = 1;
}
/* Create a label to jump to when we want to abort the query */
addrEnd = sqlite3VdbeMakeLabel(v);
/* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in
** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
** SELECT statement.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
sNC.pSrcList = pTabList;
sNC.uNC.pAggInfo = &sAggInfo;
VVA_ONLY( sNC.ncFlags = NC_UAggInfo; )
sAggInfo.mnReg = pParse->nMem+1;
sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr : 0;
sAggInfo.pGroupBy = pGroupBy;
sqlite3ExprAnalyzeAggList(&sNC, pEList);
sqlite3ExprAnalyzeAggList(&sNC, sSort.pOrderBy);
if( pHaving ){
if( pGroupBy ){
assert( pWhere==p->pWhere );
assert( pHaving==p->pHaving );
assert( pGroupBy==p->pGroupBy );
havingToWhere(pParse, p);
pWhere = p->pWhere;
}
sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
}
sAggInfo.nAccumulator = sAggInfo.nColumn;
if( p->pGroupBy==0 && p->pHaving==0 && sAggInfo.nFunc==1 ){
minMaxFlag = minMaxQuery(db, sAggInfo.aFunc[0].pExpr, &pMinMaxOrderBy);
}else{
minMaxFlag = WHERE_ORDERBY_NORMAL;
}
for(i=0; i<sAggInfo.nFunc; i++){
assert( !ExprHasProperty(sAggInfo.aFunc[i].pExpr, EP_xIsSelect) );
sNC.ncFlags |= NC_InAggFunc;
sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->x.pList);
sNC.ncFlags &= ~NC_InAggFunc;
}
sAggInfo.mxReg = pParse->nMem;
if( db->mallocFailed ) goto select_end;
#if SELECTTRACE_ENABLED
if( sqlite3SelectTrace & 0x400 ){
int ii;
SELECTTRACE(0x400,pParse,p,("After aggregate analysis:\n"));
sqlite3TreeViewSelect(0, p, 0);
for(ii=0; ii<sAggInfo.nColumn; ii++){
sqlite3DebugPrintf("agg-column[%d] iMem=%d\n",
ii, sAggInfo.aCol[ii].iMem);
sqlite3TreeViewExpr(0, sAggInfo.aCol[ii].pExpr, 0);
}
for(ii=0; ii<sAggInfo.nFunc; ii++){
sqlite3DebugPrintf("agg-func[%d]: iMem=%d\n",
ii, sAggInfo.aFunc[ii].iMem);
sqlite3TreeViewExpr(0, sAggInfo.aFunc[ii].pExpr, 0);
}
}
#endif
/* Processing for aggregates with GROUP BY is very different and
** much more complex than aggregates without a GROUP BY.
*/
if( pGroupBy ){
KeyInfo *pKeyInfo; /* Keying information for the group by clause */
int addr1; /* A-vs-B comparision jump */
int addrOutputRow; /* Start of subroutine that outputs a result row */
int regOutputRow; /* Return address register for output subroutine */
int addrSetAbort; /* Set the abort flag and return */
int addrTopOfLoop; /* Top of the input loop */
int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
int addrReset; /* Subroutine for resetting the accumulator */
int regReset; /* Return address register for reset subroutine */
/* If there is a GROUP BY clause we might need a sorting index to
** implement it. Allocate that sorting index now. If it turns out
** that we do not need it after all, the OP_SorterOpen instruction
** will be converted into a Noop.
*/
sAggInfo.sortingIdx = pParse->nTab++;
pKeyInfo = keyInfoFromExprList(pParse, pGroupBy, 0, sAggInfo.nColumn);
addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen,
sAggInfo.sortingIdx, sAggInfo.nSortingColumn,
0, (char*)pKeyInfo, P4_KEYINFO);
/* Initialize memory locations used by GROUP BY aggregate processing
*/
iUseFlag = ++pParse->nMem;
iAbortFlag = ++pParse->nMem;
regOutputRow = ++pParse->nMem;
addrOutputRow = sqlite3VdbeMakeLabel(v);
regReset = ++pParse->nMem;
addrReset = sqlite3VdbeMakeLabel(v);
iAMem = pParse->nMem + 1;
pParse->nMem += pGroupBy->nExpr;
iBMem = pParse->nMem + 1;
pParse->nMem += pGroupBy->nExpr;
sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag);
VdbeComment((v, "clear abort flag"));
sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
VdbeComment((v, "indicate accumulator empty"));
sqlite3VdbeAddOp3(v, OP_Null, 0, iAMem, iAMem+pGroupBy->nExpr-1);
/* Begin a loop that will extract all source rows in GROUP BY order.
** This might involve two separate loops with an OP_Sort in between, or
** it might be a single loop that uses an index to extract information
** in the right order to begin with.
*/
sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
SELECTTRACE(1,pParse,p,("WhereBegin\n"));
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pGroupBy, 0,
WHERE_GROUPBY | (orderByGrp ? WHERE_SORTBYGROUP : 0), 0
);
if( pWInfo==0 ) goto select_end;
if( sqlite3WhereIsOrdered(pWInfo)==pGroupBy->nExpr ){
/* The optimizer is able to deliver rows in group by order so
** we do not have to sort. The OP_OpenEphemeral table will be
** cancelled later because we still need to use the pKeyInfo
*/
groupBySort = 0;
}else{
/* Rows are coming out in undetermined order. We have to push
** each row into a sorting index, terminate the first loop,
** then loop over the sorting index in order to get the output
** in sorted order
*/
int regBase;
int regRecord;
int nCol;
int nGroupBy;
explainTempTable(pParse,
(sDistinct.isTnct && (p->selFlags&SF_Distinct)==0) ?
"DISTINCT" : "GROUP BY");
groupBySort = 1;
nGroupBy = pGroupBy->nExpr;
nCol = nGroupBy;
j = nGroupBy;
for(i=0; i<sAggInfo.nColumn; i++){
if( sAggInfo.aCol[i].iSorterColumn>=j ){
nCol++;
j++;
}
}
regBase = sqlite3GetTempRange(pParse, nCol);
sqlite3ExprCacheClear(pParse);
sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0, 0);
j = nGroupBy;
for(i=0; i<sAggInfo.nColumn; i++){
struct AggInfo_col *pCol = &sAggInfo.aCol[i];
if( pCol->iSorterColumn>=j ){
int r1 = j + regBase;
sqlite3ExprCodeGetColumnToReg(pParse,
pCol->pTab, pCol->iColumn, pCol->iTable, r1);
j++;
}
}
regRecord = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord);
sqlite3VdbeAddOp2(v, OP_SorterInsert, sAggInfo.sortingIdx, regRecord);
sqlite3ReleaseTempReg(pParse, regRecord);
sqlite3ReleaseTempRange(pParse, regBase, nCol);
sqlite3WhereEnd(pWInfo);
sAggInfo.sortingIdxPTab = sortPTab = pParse->nTab++;
sortOut = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_OpenPseudo, sortPTab, sortOut, nCol);
sqlite3VdbeAddOp2(v, OP_SorterSort, sAggInfo.sortingIdx, addrEnd);
VdbeComment((v, "GROUP BY sort")); VdbeCoverage(v);
sAggInfo.useSortingIdx = 1;
sqlite3ExprCacheClear(pParse);
}
/* If the index or temporary table used by the GROUP BY sort
** will naturally deliver rows in the order required by the ORDER BY
** clause, cancel the ephemeral table open coded earlier.
**
** This is an optimization - the correct answer should result regardless.
** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER to
** disable this optimization for testing purposes. */
if( orderByGrp && OptimizationEnabled(db, SQLITE_GroupByOrder)
&& (groupBySort || sqlite3WhereIsSorted(pWInfo))
){
sSort.pOrderBy = 0;
sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex);
}
/* Evaluate the current GROUP BY terms and store in b0, b1, b2...
** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
** Then compare the current GROUP BY terms against the GROUP BY terms
** from the previous row currently stored in a0, a1, a2...
*/
addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
sqlite3ExprCacheClear(pParse);
if( groupBySort ){
sqlite3VdbeAddOp3(v, OP_SorterData, sAggInfo.sortingIdx,
sortOut, sortPTab);
}
for(j=0; j<pGroupBy->nExpr; j++){
if( groupBySort ){
sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j);
}else{
sAggInfo.directMode = 1;
sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j);
}
}
sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr,
(char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO);
addr1 = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp3(v, OP_Jump, addr1+1, 0, addr1+1); VdbeCoverage(v);
/* Generate code that runs whenever the GROUP BY changes.
** Changes in the GROUP BY are detected by the previous code
** block. If there were no changes, this block is skipped.
**
** This code copies current group by terms in b0,b1,b2,...
** over to a0,a1,a2. It then calls the output subroutine
** and resets the aggregate accumulator registers in preparation
** for the next GROUP BY batch.
*/
sqlite3ExprCodeMove(pParse, iBMem, iAMem, pGroupBy->nExpr);
sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
VdbeComment((v, "output one row"));
sqlite3VdbeAddOp2(v, OP_IfPos, iAbortFlag, addrEnd); VdbeCoverage(v);
VdbeComment((v, "check abort flag"));
sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
VdbeComment((v, "reset accumulator"));
/* Update the aggregate accumulators based on the content of
** the current row
*/
sqlite3VdbeJumpHere(v, addr1);
updateAccumulator(pParse, &sAggInfo);
sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
VdbeComment((v, "indicate data in accumulator"));
/* End of the loop
*/
if( groupBySort ){
sqlite3VdbeAddOp2(v, OP_SorterNext, sAggInfo.sortingIdx, addrTopOfLoop);
VdbeCoverage(v);
}else{
sqlite3WhereEnd(pWInfo);
sqlite3VdbeChangeToNoop(v, addrSortingIdx);
}
/* Output the final row of result
*/
sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
VdbeComment((v, "output final row"));
/* Jump over the subroutines
*/
sqlite3VdbeGoto(v, addrEnd);
/* Generate a subroutine that outputs a single row of the result
** set. This subroutine first looks at the iUseFlag. If iUseFlag
** is less than or equal to zero, the subroutine is a no-op. If
** the processing calls for the query to abort, this subroutine
** increments the iAbortFlag memory location before returning in
** order to signal the caller to abort.
*/
addrSetAbort = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
VdbeComment((v, "set abort flag"));
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
sqlite3VdbeResolveLabel(v, addrOutputRow);
addrOutputRow = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
VdbeCoverage(v);
VdbeComment((v, "Groupby result generator entry point"));
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
finalizeAggFunctions(pParse, &sAggInfo);
sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
selectInnerLoop(pParse, p, -1, &sSort,
&sDistinct, pDest,
addrOutputRow+1, addrSetAbort);
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
VdbeComment((v, "end groupby result generator"));
/* Generate a subroutine that will reset the group-by accumulator
*/
sqlite3VdbeResolveLabel(v, addrReset);
resetAccumulator(pParse, &sAggInfo);
sqlite3VdbeAddOp1(v, OP_Return, regReset);
} /* endif pGroupBy. Begin aggregate queries without GROUP BY: */
else {
#ifndef SQLITE_OMIT_BTREECOUNT
Table *pTab;
if( (pTab = isSimpleCount(p, &sAggInfo))!=0 ){
/* If isSimpleCount() returns a pointer to a Table structure, then
** the SQL statement is of the form:
**
** SELECT count(*) FROM <tbl>
**
** where the Table structure returned represents table <tbl>.
**
** This statement is so common that it is optimized specially. The
** OP_Count instruction is executed either on the intkey table that
** contains the data for table <tbl> or on one of its indexes. It
** is better to execute the op on an index, as indexes are almost
** always spread across less pages than their corresponding tables.
*/
const int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
const int iCsr = pParse->nTab++; /* Cursor to scan b-tree */
Index *pIdx; /* Iterator variable */
KeyInfo *pKeyInfo = 0; /* Keyinfo for scanned index */
Index *pBest = 0; /* Best index found so far */
int iRoot = pTab->tnum; /* Root page of scanned b-tree */
sqlite3CodeVerifySchema(pParse, iDb);
sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
/* Search for the index that has the lowest scan cost.
**
** (2011-04-15) Do not do a full scan of an unordered index.
**
** (2013-10-03) Do not count the entries in a partial index.
**
** In practice the KeyInfo structure will not be used. It is only
** passed to keep OP_OpenRead happy.
*/
if( !HasRowid(pTab) ) pBest = sqlite3PrimaryKeyIndex(pTab);
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
if( pIdx->bUnordered==0
&& pIdx->szIdxRow<pTab->szTabRow
&& pIdx->pPartIdxWhere==0
&& (!pBest || pIdx->szIdxRow<pBest->szIdxRow)
){
pBest = pIdx;
}
}
if( pBest ){
iRoot = pBest->tnum;
pKeyInfo = sqlite3KeyInfoOfIndex(pParse, pBest);
}
/* Open a read-only cursor, execute the OP_Count, close the cursor. */
sqlite3VdbeAddOp4Int(v, OP_OpenRead, iCsr, iRoot, iDb, 1);
if( pKeyInfo ){
sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO);
}
sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem);
sqlite3VdbeAddOp1(v, OP_Close, iCsr);
explainSimpleCount(pParse, pTab, pBest);
}else
#endif /* SQLITE_OMIT_BTREECOUNT */
{
/* This case runs if the aggregate has no GROUP BY clause. The
** processing is much simpler since there is only a single row
** of output.
*/
assert( p->pGroupBy==0 );
resetAccumulator(pParse, &sAggInfo);
/* If this query is a candidate for the min/max optimization, then
** minMaxFlag will have been previously set to either
** WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX and pMinMaxOrderBy will
** be an appropriate ORDER BY expression for the optimization.
*/
assert( minMaxFlag==WHERE_ORDERBY_NORMAL || pMinMaxOrderBy!=0 );
assert( pMinMaxOrderBy==0 || pMinMaxOrderBy->nExpr==1 );
SELECTTRACE(1,pParse,p,("WhereBegin\n"));
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMaxOrderBy,
0, minMaxFlag, 0);
if( pWInfo==0 ){
goto select_end;
}
updateAccumulator(pParse, &sAggInfo);
if( sqlite3WhereIsOrdered(pWInfo)>0 ){
sqlite3VdbeGoto(v, sqlite3WhereBreakLabel(pWInfo));
VdbeComment((v, "%s() by index",
(minMaxFlag==WHERE_ORDERBY_MIN?"min":"max")));
}
sqlite3WhereEnd(pWInfo);
finalizeAggFunctions(pParse, &sAggInfo);
}
sSort.pOrderBy = 0;
sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
selectInnerLoop(pParse, p, -1, 0, 0,
pDest, addrEnd, addrEnd);
}
sqlite3VdbeResolveLabel(v, addrEnd);
} /* endif aggregate query */
if( sDistinct.eTnctType==WHERE_DISTINCT_UNORDERED ){
explainTempTable(pParse, "DISTINCT");
}
/* If there is an ORDER BY clause, then we need to sort the results
** and send them to the callback one by one.
*/
if( sSort.pOrderBy ){
explainTempTable(pParse,
sSort.nOBSat>0 ? "RIGHT PART OF ORDER BY":"ORDER BY");
assert( p->pEList==pEList );
generateSortTail(pParse, p, &sSort, pEList->nExpr, pDest);
}
/* Jump here to skip this query
*/
sqlite3VdbeResolveLabel(v, iEnd);
/* The SELECT has been coded. If there is an error in the Parse structure,
** set the return code to 1. Otherwise 0. */
rc = (pParse->nErr>0);
/* Control jumps to here if an error is encountered above, or upon
** successful coding of the SELECT.
*/
select_end:
sqlite3ExprListDelete(db, pMinMaxOrderBy);
sqlite3DbFree(db, sAggInfo.aCol);
sqlite3DbFree(db, sAggInfo.aFunc);
#if SELECTTRACE_ENABLED
SELECTTRACE(0x1,pParse,p,("end processing\n"));
if( (sqlite3SelectTrace & 0x2000)!=0 && ExplainQueryPlanParent(pParse)==0 ){
sqlite3TreeViewSelect(0, p, 0);
}
#endif
ExplainQueryPlanPop(pParse);
return rc;
}
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