Files
sqlite/src/delete.c
T
drh 33e619fc1c Additional refinements to Expr handling. Restore compression of trigger
expressions.  Change Expr.zToken to Expr.u.zToken and added Expr.u.iValue.
Remove an unnecessary ExprDup from CHECK constraint processing.  And so forth. (CVS 6682)

FossilOrigin-Name: 4ac2bdfbb4230b6ceaae87e738fa61036bbe03cb
2009-05-28 01:00:55 +00:00

618 lines
21 KiB
C

/*
** 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
** in order to generate code for DELETE FROM statements.
**
** $Id: delete.c,v 1.203 2009/05/28 01:00:55 drh Exp $
*/
#include "sqliteInt.h"
/*
** Look up every table that is named in pSrc. If any table is not found,
** add an error message to pParse->zErrMsg and return NULL. If all tables
** are found, return a pointer to the last table.
*/
Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
struct SrcList_item *pItem = pSrc->a;
Table *pTab;
assert( pItem && pSrc->nSrc==1 );
pTab = sqlite3LocateTable(pParse, 0, pItem->zName, pItem->zDatabase);
sqlite3DeleteTable(pItem->pTab);
pItem->pTab = pTab;
if( pTab ){
pTab->nRef++;
}
if( sqlite3IndexedByLookup(pParse, pItem) ){
pTab = 0;
}
return pTab;
}
/*
** Check to make sure the given table is writable. If it is not
** writable, generate an error message and return 1. If it is
** writable return 0;
*/
int sqlite3IsReadOnly(Parse *pParse, Table *pTab, int viewOk){
if( ((pTab->tabFlags & TF_Readonly)!=0
&& (pParse->db->flags & SQLITE_WriteSchema)==0
&& pParse->nested==0)
#ifndef SQLITE_OMIT_VIRTUALTABLE
|| (pTab->pMod && pTab->pMod->pModule->xUpdate==0)
#endif
){
sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
return 1;
}
#ifndef SQLITE_OMIT_VIEW
if( !viewOk && pTab->pSelect ){
sqlite3ErrorMsg(pParse,"cannot modify %s because it is a view",pTab->zName);
return 1;
}
#endif
return 0;
}
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
/*
** Evaluate a view and store its result in an ephemeral table. The
** pWhere argument is an optional WHERE clause that restricts the
** set of rows in the view that are to be added to the ephemeral table.
*/
void sqlite3MaterializeView(
Parse *pParse, /* Parsing context */
Table *pView, /* View definition */
Expr *pWhere, /* Optional WHERE clause to be added */
int iCur /* Cursor number for ephemerial table */
){
SelectDest dest;
Select *pDup;
sqlite3 *db = pParse->db;
pDup = sqlite3SelectDup(db, pView->pSelect, 0);
if( pWhere ){
SrcList *pFrom;
pWhere = sqlite3ExprDup(db, pWhere, 0);
pFrom = sqlite3SrcListAppend(db, 0, 0, 0);
if( pFrom ){
assert( pFrom->nSrc==1 );
pFrom->a[0].zAlias = sqlite3DbStrDup(db, pView->zName);
pFrom->a[0].pSelect = pDup;
assert( pFrom->a[0].pOn==0 );
assert( pFrom->a[0].pUsing==0 );
}else{
sqlite3SelectDelete(db, pDup);
}
pDup = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, 0, 0, 0, 0);
}
sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
sqlite3Select(pParse, pDup, &dest);
sqlite3SelectDelete(db, pDup);
}
#endif /* !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) */
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
/*
** Generate an expression tree to implement the WHERE, ORDER BY,
** and LIMIT/OFFSET portion of DELETE and UPDATE statements.
**
** DELETE FROM table_wxyz WHERE a<5 ORDER BY a LIMIT 1;
** \__________________________/
** pLimitWhere (pInClause)
*/
Expr *sqlite3LimitWhere(
Parse *pParse, /* The parser context */
SrcList *pSrc, /* the FROM clause -- which tables to scan */
Expr *pWhere, /* The WHERE clause. May be null */
ExprList *pOrderBy, /* The ORDER BY clause. May be null */
Expr *pLimit, /* The LIMIT clause. May be null */
Expr *pOffset, /* The OFFSET clause. May be null */
char *zStmtType /* Either DELETE or UPDATE. For error messages. */
){
Expr *pWhereRowid = NULL; /* WHERE rowid .. */
Expr *pInClause = NULL; /* WHERE rowid IN ( select ) */
Expr *pSelectRowid = NULL; /* SELECT rowid ... */
ExprList *pEList = NULL; /* Expression list contaning only pSelectRowid */
SrcList *pSelectSrc = NULL; /* SELECT rowid FROM x ... (dup of pSrc) */
Select *pSelect = NULL; /* Complete SELECT tree */
/* Check that there isn't an ORDER BY without a LIMIT clause.
*/
if( pOrderBy && (pLimit == 0) ) {
sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
pParse->parseError = 1;
goto limit_where_cleanup_2;
}
/* We only need to generate a select expression if there
** is a limit/offset term to enforce.
*/
if( pLimit == 0 ) {
/* if pLimit is null, pOffset will always be null as well. */
assert( pOffset == 0 );
return pWhere;
}
/* Generate a select expression tree to enforce the limit/offset
** term for the DELETE or UPDATE statement. For example:
** DELETE FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
** becomes:
** DELETE FROM table_a WHERE rowid IN (
** SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
** );
*/
pSelectRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);
if( pSelectRowid == 0 ) goto limit_where_cleanup_2;
pEList = sqlite3ExprListAppend(pParse, 0, pSelectRowid);
if( pEList == 0 ) goto limit_where_cleanup_2;
/* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
** and the SELECT subtree. */
pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc, 0);
if( pSelectSrc == 0 ) {
sqlite3ExprListDelete(pParse->db, pEList);
goto limit_where_cleanup_2;
}
/* generate the SELECT expression tree. */
pSelect = sqlite3SelectNew(pParse,pEList,pSelectSrc,pWhere,0,0,
pOrderBy,0,pLimit,pOffset);
if( pSelect == 0 ) return 0;
/* now generate the new WHERE rowid IN clause for the DELETE/UDPATE */
pWhereRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);
if( pWhereRowid == 0 ) goto limit_where_cleanup_1;
pInClause = sqlite3PExpr(pParse, TK_IN, pWhereRowid, 0, 0);
if( pInClause == 0 ) goto limit_where_cleanup_1;
pInClause->x.pSelect = pSelect;
pInClause->flags |= EP_xIsSelect;
sqlite3ExprSetHeight(pParse, pInClause);
return pInClause;
/* something went wrong. clean up anything allocated. */
limit_where_cleanup_1:
sqlite3SelectDelete(pParse->db, pSelect);
return 0;
limit_where_cleanup_2:
sqlite3ExprDelete(pParse->db, pWhere);
sqlite3ExprListDelete(pParse->db, pOrderBy);
sqlite3ExprDelete(pParse->db, pLimit);
sqlite3ExprDelete(pParse->db, pOffset);
return 0;
}
#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY) */
/*
** Generate code for a DELETE FROM statement.
**
** DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL;
** \________/ \________________/
** pTabList pWhere
*/
void sqlite3DeleteFrom(
Parse *pParse, /* The parser context */
SrcList *pTabList, /* The table from which we should delete things */
Expr *pWhere /* The WHERE clause. May be null */
){
Vdbe *v; /* The virtual database engine */
Table *pTab; /* The table from which records will be deleted */
const char *zDb; /* Name of database holding pTab */
int end, addr = 0; /* A couple addresses of generated code */
int i; /* Loop counter */
WhereInfo *pWInfo; /* Information about the WHERE clause */
Index *pIdx; /* For looping over indices of the table */
int iCur; /* VDBE Cursor number for pTab */
sqlite3 *db; /* Main database structure */
AuthContext sContext; /* Authorization context */
int oldIdx = -1; /* Cursor for the OLD table of AFTER triggers */
NameContext sNC; /* Name context to resolve expressions in */
int iDb; /* Database number */
int memCnt = -1; /* Memory cell used for change counting */
int rcauth; /* Value returned by authorization callback */
#ifndef SQLITE_OMIT_TRIGGER
int isView; /* True if attempting to delete from a view */
Trigger *pTrigger; /* List of table triggers, if required */
#endif
int iBeginAfterTrigger = 0; /* Address of after trigger program */
int iEndAfterTrigger = 0; /* Exit of after trigger program */
int iBeginBeforeTrigger = 0; /* Address of before trigger program */
int iEndBeforeTrigger = 0; /* Exit of before trigger program */
u32 old_col_mask = 0; /* Mask of OLD.* columns in use */
sContext.pParse = 0;
db = pParse->db;
if( pParse->nErr || db->mallocFailed ){
goto delete_from_cleanup;
}
assert( pTabList->nSrc==1 );
/* Locate the table which we want to delete. This table has to be
** put in an SrcList structure because some of the subroutines we
** will be calling are designed to work with multiple tables and expect
** an SrcList* parameter instead of just a Table* parameter.
*/
pTab = sqlite3SrcListLookup(pParse, pTabList);
if( pTab==0 ) goto delete_from_cleanup;
/* Figure out if we have any triggers and if the table being
** deleted from is a view
*/
#ifndef SQLITE_OMIT_TRIGGER
pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
isView = pTab->pSelect!=0;
#else
# define pTrigger 0
# define isView 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif
if( sqlite3IsReadOnly(pParse, pTab, (pTrigger?1:0)) ){
goto delete_from_cleanup;
}
iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
assert( iDb<db->nDb );
zDb = db->aDb[iDb].zName;
rcauth = sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb);
assert( rcauth==SQLITE_OK || rcauth==SQLITE_DENY || rcauth==SQLITE_IGNORE );
if( rcauth==SQLITE_DENY ){
goto delete_from_cleanup;
}
assert(!isView || pTrigger);
/* If pTab is really a view, make sure it has been initialized.
*/
if( sqlite3ViewGetColumnNames(pParse, pTab) ){
goto delete_from_cleanup;
}
/* Allocate a cursor used to store the old.* data for a trigger.
*/
if( pTrigger ){
oldIdx = pParse->nTab++;
}
/* Assign cursor number to the table and all its indices.
*/
assert( pTabList->nSrc==1 );
iCur = pTabList->a[0].iCursor = pParse->nTab++;
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
pParse->nTab++;
}
/* Start the view context
*/
if( isView ){
sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
}
/* Begin generating code.
*/
v = sqlite3GetVdbe(pParse);
if( v==0 ){
goto delete_from_cleanup;
}
if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
sqlite3BeginWriteOperation(pParse, (pTrigger?1:0), iDb);
if( pTrigger ){
int orconf = ((pParse->trigStack)?pParse->trigStack->orconf:OE_Default);
int iGoto = sqlite3VdbeAddOp0(v, OP_Goto);
addr = sqlite3VdbeMakeLabel(v);
iBeginBeforeTrigger = sqlite3VdbeCurrentAddr(v);
(void)sqlite3CodeRowTrigger(pParse, pTrigger, TK_DELETE, 0,
TRIGGER_BEFORE, pTab, -1, oldIdx, orconf, addr, &old_col_mask, 0);
iEndBeforeTrigger = sqlite3VdbeAddOp0(v, OP_Goto);
iBeginAfterTrigger = sqlite3VdbeCurrentAddr(v);
(void)sqlite3CodeRowTrigger(pParse, pTrigger, TK_DELETE, 0,
TRIGGER_AFTER, pTab, -1, oldIdx, orconf, addr, &old_col_mask, 0);
iEndAfterTrigger = sqlite3VdbeAddOp0(v, OP_Goto);
sqlite3VdbeJumpHere(v, iGoto);
}
/* If we are trying to delete from a view, realize that view into
** a ephemeral table.
*/
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
if( isView ){
sqlite3MaterializeView(pParse, pTab, pWhere, iCur);
}
#endif
/* Resolve the column names in the WHERE clause.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
sNC.pSrcList = pTabList;
if( sqlite3ResolveExprNames(&sNC, pWhere) ){
goto delete_from_cleanup;
}
/* Initialize the counter of the number of rows deleted, if
** we are counting rows.
*/
if( db->flags & SQLITE_CountRows ){
memCnt = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Integer, 0, memCnt);
}
#ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION
/* Special case: A DELETE without a WHERE clause deletes everything.
** It is easier just to erase the whole table. Note, however, that
** this means that the row change count will be incorrect.
*/
if( rcauth==SQLITE_OK && pWhere==0 && !pTrigger && !IsVirtual(pTab) ){
assert( !isView );
sqlite3VdbeAddOp4(v, OP_Clear, pTab->tnum, iDb, memCnt,
pTab->zName, P4_STATIC);
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
assert( pIdx->pSchema==pTab->pSchema );
sqlite3VdbeAddOp2(v, OP_Clear, pIdx->tnum, iDb);
}
}else
#endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */
/* The usual case: There is a WHERE clause so we have to scan through
** the table and pick which records to delete.
*/
{
int iRowid = ++pParse->nMem; /* Used for storing rowid values. */
int iRowSet = ++pParse->nMem; /* Register for rowset of rows to delete */
int regRowid; /* Actual register containing rowids */
/* Collect rowids of every row to be deleted.
*/
sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere,0,WHERE_DUPLICATES_OK);
if( pWInfo==0 ) goto delete_from_cleanup;
regRowid = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, iRowid, 0);
sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, regRowid);
if( db->flags & SQLITE_CountRows ){
sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
}
sqlite3WhereEnd(pWInfo);
/* Open the pseudo-table used to store OLD if there are triggers.
*/
if( pTrigger ){
sqlite3VdbeAddOp3(v, OP_OpenPseudo, oldIdx, 0, pTab->nCol);
}
/* Delete every item whose key was written to the list during the
** database scan. We have to delete items after the scan is complete
** because deleting an item can change the scan order.
*/
end = sqlite3VdbeMakeLabel(v);
if( !isView ){
/* Open cursors for the table we are deleting from and
** all its indices.
*/
sqlite3OpenTableAndIndices(pParse, pTab, iCur, OP_OpenWrite);
}
/* This is the beginning of the delete loop. If a trigger encounters
** an IGNORE constraint, it jumps back to here.
*/
if( pTrigger ){
sqlite3VdbeResolveLabel(v, addr);
}
addr = sqlite3VdbeAddOp3(v, OP_RowSetRead, iRowSet, end, iRowid);
if( pTrigger ){
int iData = ++pParse->nMem; /* For storing row data of OLD table */
/* If the record is no longer present in the table, jump to the
** next iteration of the loop through the contents of the fifo.
*/
sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, iRowid);
/* Populate the OLD.* pseudo-table */
if( old_col_mask ){
sqlite3VdbeAddOp2(v, OP_RowData, iCur, iData);
}else{
sqlite3VdbeAddOp2(v, OP_Null, 0, iData);
}
sqlite3VdbeAddOp3(v, OP_Insert, oldIdx, iData, iRowid);
/* Jump back and run the BEFORE triggers */
sqlite3VdbeAddOp2(v, OP_Goto, 0, iBeginBeforeTrigger);
sqlite3VdbeJumpHere(v, iEndBeforeTrigger);
}
if( !isView ){
/* Delete the row */
#ifndef SQLITE_OMIT_VIRTUALTABLE
if( IsVirtual(pTab) ){
const char *pVtab = (const char *)pTab->pVtab;
sqlite3VtabMakeWritable(pParse, pTab);
sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iRowid, pVtab, P4_VTAB);
}else
#endif
{
sqlite3GenerateRowDelete(pParse, pTab, iCur, iRowid, pParse->nested==0);
}
}
/* If there are row triggers, close all cursors then invoke
** the AFTER triggers
*/
if( pTrigger ){
/* Jump back and run the AFTER triggers */
sqlite3VdbeAddOp2(v, OP_Goto, 0, iBeginAfterTrigger);
sqlite3VdbeJumpHere(v, iEndAfterTrigger);
}
/* End of the delete loop */
sqlite3VdbeAddOp2(v, OP_Goto, 0, addr);
sqlite3VdbeResolveLabel(v, end);
/* Close the cursors after the loop if there are no row triggers */
if( !isView && !IsVirtual(pTab) ){
for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
sqlite3VdbeAddOp2(v, OP_Close, iCur + i, pIdx->tnum);
}
sqlite3VdbeAddOp1(v, OP_Close, iCur);
}
}
/*
** Return the number of rows that were deleted. If this routine is
** generating code because of a call to sqlite3NestedParse(), do not
** invoke the callback function.
*/
if( db->flags & SQLITE_CountRows && pParse->nested==0 && !pParse->trigStack ){
sqlite3VdbeAddOp2(v, OP_ResultRow, memCnt, 1);
sqlite3VdbeSetNumCols(v, 1);
sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows deleted", SQLITE_STATIC);
}
delete_from_cleanup:
sqlite3AuthContextPop(&sContext);
sqlite3SrcListDelete(db, pTabList);
sqlite3ExprDelete(db, pWhere);
return;
}
/*
** This routine generates VDBE code that causes a single row of a
** single table to be deleted.
**
** The VDBE must be in a particular state when this routine is called.
** These are the requirements:
**
** 1. A read/write cursor pointing to pTab, the table containing the row
** to be deleted, must be opened as cursor number "base".
**
** 2. Read/write cursors for all indices of pTab must be open as
** cursor number base+i for the i-th index.
**
** 3. The record number of the row to be deleted must be stored in
** memory cell iRowid.
**
** This routine pops the top of the stack to remove the record number
** and then generates code to remove both the table record and all index
** entries that point to that record.
*/
void sqlite3GenerateRowDelete(
Parse *pParse, /* Parsing context */
Table *pTab, /* Table containing the row to be deleted */
int iCur, /* Cursor number for the table */
int iRowid, /* Memory cell that contains the rowid to delete */
int count /* Increment the row change counter */
){
int addr;
Vdbe *v;
v = pParse->pVdbe;
addr = sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, iRowid);
sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, 0);
sqlite3VdbeAddOp2(v, OP_Delete, iCur, (count?OPFLAG_NCHANGE:0));
if( count ){
sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);
}
sqlite3VdbeJumpHere(v, addr);
}
/*
** This routine generates VDBE code that causes the deletion of all
** index entries associated with a single row of a single table.
**
** The VDBE must be in a particular state when this routine is called.
** These are the requirements:
**
** 1. A read/write cursor pointing to pTab, the table containing the row
** to be deleted, must be opened as cursor number "iCur".
**
** 2. Read/write cursors for all indices of pTab must be open as
** cursor number iCur+i for the i-th index.
**
** 3. The "iCur" cursor must be pointing to the row that is to be
** deleted.
*/
void sqlite3GenerateRowIndexDelete(
Parse *pParse, /* Parsing and code generating context */
Table *pTab, /* Table containing the row to be deleted */
int iCur, /* Cursor number for the table */
int *aRegIdx /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
){
int i;
Index *pIdx;
int r1;
for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
if( aRegIdx!=0 && aRegIdx[i-1]==0 ) continue;
r1 = sqlite3GenerateIndexKey(pParse, pIdx, iCur, 0, 0);
sqlite3VdbeAddOp3(pParse->pVdbe, OP_IdxDelete, iCur+i, r1,pIdx->nColumn+1);
}
}
/*
** Generate code that will assemble an index key and put it in register
** regOut. The key with be for index pIdx which is an index on pTab.
** iCur is the index of a cursor open on the pTab table and pointing to
** the entry that needs indexing.
**
** Return a register number which is the first in a block of
** registers that holds the elements of the index key. The
** block of registers has already been deallocated by the time
** this routine returns.
*/
int sqlite3GenerateIndexKey(
Parse *pParse, /* Parsing context */
Index *pIdx, /* The index for which to generate a key */
int iCur, /* Cursor number for the pIdx->pTable table */
int regOut, /* Write the new index key to this register */
int doMakeRec /* Run the OP_MakeRecord instruction if true */
){
Vdbe *v = pParse->pVdbe;
int j;
Table *pTab = pIdx->pTable;
int regBase;
int nCol;
nCol = pIdx->nColumn;
regBase = sqlite3GetTempRange(pParse, nCol+1);
sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regBase+nCol);
for(j=0; j<nCol; j++){
int idx = pIdx->aiColumn[j];
if( idx==pTab->iPKey ){
sqlite3VdbeAddOp2(v, OP_SCopy, regBase+nCol, regBase+j);
}else{
sqlite3VdbeAddOp3(v, OP_Column, iCur, idx, regBase+j);
sqlite3ColumnDefault(v, pTab, idx);
}
}
if( doMakeRec ){
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol+1, regOut);
sqlite3IndexAffinityStr(v, pIdx);
sqlite3ExprCacheAffinityChange(pParse, regBase, nCol+1);
}
sqlite3ReleaseTempRange(pParse, regBase, nCol+1);
return regBase;
}
/* Make sure "isView" gets undefined in case this file becomes part of
** the amalgamation - so that subsequent files do not see isView as a
** macro. */
#undef isView