drh
33e619fc1c
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
3585 lines
132 KiB
C
3585 lines
132 KiB
C
/*
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** 2001 September 15
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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** This module contains C code that generates VDBE code used to process
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** the WHERE clause of SQL statements. This module is responsible for
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** generating the code that loops through a table looking for applicable
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** rows. Indices are selected and used to speed the search when doing
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** so is applicable. Because this module is responsible for selecting
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** indices, you might also think of this module as the "query optimizer".
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**
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** $Id: where.c,v 1.399 2009/05/28 01:00:55 drh Exp $
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*/
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#include "sqliteInt.h"
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/*
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** Trace output macros
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*/
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#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
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int sqlite3WhereTrace = 0;
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#endif
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#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
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# define WHERETRACE(X) if(sqlite3WhereTrace) sqlite3DebugPrintf X
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#else
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# define WHERETRACE(X)
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#endif
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/* Forward reference
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*/
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typedef struct WhereClause WhereClause;
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typedef struct WhereMaskSet WhereMaskSet;
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typedef struct WhereOrInfo WhereOrInfo;
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typedef struct WhereAndInfo WhereAndInfo;
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typedef struct WhereCost WhereCost;
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/*
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** The query generator uses an array of instances of this structure to
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** help it analyze the subexpressions of the WHERE clause. Each WHERE
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** clause subexpression is separated from the others by AND operators,
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** usually, or sometimes subexpressions separated by OR.
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**
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** All WhereTerms are collected into a single WhereClause structure.
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** The following identity holds:
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**
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** WhereTerm.pWC->a[WhereTerm.idx] == WhereTerm
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**
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** When a term is of the form:
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**
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** X <op> <expr>
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**
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** where X is a column name and <op> is one of certain operators,
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** then WhereTerm.leftCursor and WhereTerm.u.leftColumn record the
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** cursor number and column number for X. WhereTerm.eOperator records
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** the <op> using a bitmask encoding defined by WO_xxx below. The
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** use of a bitmask encoding for the operator allows us to search
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** quickly for terms that match any of several different operators.
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**
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** A WhereTerm might also be two or more subterms connected by OR:
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**
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** (t1.X <op> <expr>) OR (t1.Y <op> <expr>) OR ....
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**
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** In this second case, wtFlag as the TERM_ORINFO set and eOperator==WO_OR
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** and the WhereTerm.u.pOrInfo field points to auxiliary information that
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** is collected about the
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**
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** If a term in the WHERE clause does not match either of the two previous
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** categories, then eOperator==0. The WhereTerm.pExpr field is still set
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** to the original subexpression content and wtFlags is set up appropriately
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** but no other fields in the WhereTerm object are meaningful.
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**
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** When eOperator!=0, prereqRight and prereqAll record sets of cursor numbers,
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** but they do so indirectly. A single WhereMaskSet structure translates
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** cursor number into bits and the translated bit is stored in the prereq
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** fields. The translation is used in order to maximize the number of
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** bits that will fit in a Bitmask. The VDBE cursor numbers might be
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** spread out over the non-negative integers. For example, the cursor
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** numbers might be 3, 8, 9, 10, 20, 23, 41, and 45. The WhereMaskSet
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** translates these sparse cursor numbers into consecutive integers
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** beginning with 0 in order to make the best possible use of the available
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** bits in the Bitmask. So, in the example above, the cursor numbers
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** would be mapped into integers 0 through 7.
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**
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** The number of terms in a join is limited by the number of bits
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** in prereqRight and prereqAll. The default is 64 bits, hence SQLite
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** is only able to process joins with 64 or fewer tables.
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*/
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typedef struct WhereTerm WhereTerm;
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struct WhereTerm {
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Expr *pExpr; /* Pointer to the subexpression that is this term */
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int iParent; /* Disable pWC->a[iParent] when this term disabled */
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int leftCursor; /* Cursor number of X in "X <op> <expr>" */
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union {
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int leftColumn; /* Column number of X in "X <op> <expr>" */
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WhereOrInfo *pOrInfo; /* Extra information if eOperator==WO_OR */
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WhereAndInfo *pAndInfo; /* Extra information if eOperator==WO_AND */
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} u;
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u16 eOperator; /* A WO_xx value describing <op> */
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u8 wtFlags; /* TERM_xxx bit flags. See below */
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u8 nChild; /* Number of children that must disable us */
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WhereClause *pWC; /* The clause this term is part of */
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Bitmask prereqRight; /* Bitmask of tables used by pExpr->pRight */
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Bitmask prereqAll; /* Bitmask of tables referenced by pExpr */
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};
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/*
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** Allowed values of WhereTerm.wtFlags
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*/
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#define TERM_DYNAMIC 0x01 /* Need to call sqlite3ExprDelete(db, pExpr) */
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#define TERM_VIRTUAL 0x02 /* Added by the optimizer. Do not code */
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#define TERM_CODED 0x04 /* This term is already coded */
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#define TERM_COPIED 0x08 /* Has a child */
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#define TERM_ORINFO 0x10 /* Need to free the WhereTerm.u.pOrInfo object */
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#define TERM_ANDINFO 0x20 /* Need to free the WhereTerm.u.pAndInfo obj */
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#define TERM_OR_OK 0x40 /* Used during OR-clause processing */
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/*
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** An instance of the following structure holds all information about a
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** WHERE clause. Mostly this is a container for one or more WhereTerms.
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*/
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struct WhereClause {
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Parse *pParse; /* The parser context */
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WhereMaskSet *pMaskSet; /* Mapping of table cursor numbers to bitmasks */
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Bitmask vmask; /* Bitmask identifying virtual table cursors */
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u8 op; /* Split operator. TK_AND or TK_OR */
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int nTerm; /* Number of terms */
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int nSlot; /* Number of entries in a[] */
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WhereTerm *a; /* Each a[] describes a term of the WHERE cluase */
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WhereTerm aStatic[4]; /* Initial static space for a[] */
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};
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/*
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** A WhereTerm with eOperator==WO_OR has its u.pOrInfo pointer set to
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** a dynamically allocated instance of the following structure.
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*/
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struct WhereOrInfo {
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WhereClause wc; /* Decomposition into subterms */
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Bitmask indexable; /* Bitmask of all indexable tables in the clause */
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};
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/*
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** A WhereTerm with eOperator==WO_AND has its u.pAndInfo pointer set to
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** a dynamically allocated instance of the following structure.
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*/
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struct WhereAndInfo {
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WhereClause wc; /* The subexpression broken out */
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};
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/*
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** An instance of the following structure keeps track of a mapping
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** between VDBE cursor numbers and bits of the bitmasks in WhereTerm.
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**
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** The VDBE cursor numbers are small integers contained in
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** SrcList_item.iCursor and Expr.iTable fields. For any given WHERE
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** clause, the cursor numbers might not begin with 0 and they might
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** contain gaps in the numbering sequence. But we want to make maximum
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** use of the bits in our bitmasks. This structure provides a mapping
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** from the sparse cursor numbers into consecutive integers beginning
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** with 0.
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**
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** If WhereMaskSet.ix[A]==B it means that The A-th bit of a Bitmask
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** corresponds VDBE cursor number B. The A-th bit of a bitmask is 1<<A.
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**
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** For example, if the WHERE clause expression used these VDBE
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** cursors: 4, 5, 8, 29, 57, 73. Then the WhereMaskSet structure
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** would map those cursor numbers into bits 0 through 5.
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**
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** Note that the mapping is not necessarily ordered. In the example
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** above, the mapping might go like this: 4->3, 5->1, 8->2, 29->0,
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** 57->5, 73->4. Or one of 719 other combinations might be used. It
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** does not really matter. What is important is that sparse cursor
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** numbers all get mapped into bit numbers that begin with 0 and contain
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** no gaps.
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*/
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struct WhereMaskSet {
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int n; /* Number of assigned cursor values */
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int ix[BMS]; /* Cursor assigned to each bit */
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};
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/*
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** A WhereCost object records a lookup strategy and the estimated
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** cost of pursuing that strategy.
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*/
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struct WhereCost {
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WherePlan plan; /* The lookup strategy */
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double rCost; /* Overall cost of pursuing this search strategy */
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double nRow; /* Estimated number of output rows */
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};
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/*
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** Bitmasks for the operators that indices are able to exploit. An
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** OR-ed combination of these values can be used when searching for
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** terms in the where clause.
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*/
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#define WO_IN 0x001
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#define WO_EQ 0x002
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#define WO_LT (WO_EQ<<(TK_LT-TK_EQ))
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#define WO_LE (WO_EQ<<(TK_LE-TK_EQ))
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#define WO_GT (WO_EQ<<(TK_GT-TK_EQ))
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#define WO_GE (WO_EQ<<(TK_GE-TK_EQ))
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#define WO_MATCH 0x040
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#define WO_ISNULL 0x080
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#define WO_OR 0x100 /* Two or more OR-connected terms */
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#define WO_AND 0x200 /* Two or more AND-connected terms */
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#define WO_ALL 0xfff /* Mask of all possible WO_* values */
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#define WO_SINGLE 0x0ff /* Mask of all non-compound WO_* values */
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/*
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** Value for wsFlags returned by bestIndex() and stored in
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** WhereLevel.wsFlags. These flags determine which search
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** strategies are appropriate.
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**
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** The least significant 12 bits is reserved as a mask for WO_ values above.
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** The WhereLevel.wsFlags field is usually set to WO_IN|WO_EQ|WO_ISNULL.
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** But if the table is the right table of a left join, WhereLevel.wsFlags
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** is set to WO_IN|WO_EQ. The WhereLevel.wsFlags field can then be used as
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** the "op" parameter to findTerm when we are resolving equality constraints.
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** ISNULL constraints will then not be used on the right table of a left
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** join. Tickets #2177 and #2189.
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*/
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#define WHERE_ROWID_EQ 0x00001000 /* rowid=EXPR or rowid IN (...) */
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#define WHERE_ROWID_RANGE 0x00002000 /* rowid<EXPR and/or rowid>EXPR */
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#define WHERE_COLUMN_EQ 0x00010000 /* x=EXPR or x IN (...) or x IS NULL */
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#define WHERE_COLUMN_RANGE 0x00020000 /* x<EXPR and/or x>EXPR */
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#define WHERE_COLUMN_IN 0x00040000 /* x IN (...) */
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#define WHERE_COLUMN_NULL 0x00080000 /* x IS NULL */
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#define WHERE_INDEXED 0x000f0000 /* Anything that uses an index */
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#define WHERE_IN_ABLE 0x000f1000 /* Able to support an IN operator */
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#define WHERE_TOP_LIMIT 0x00100000 /* x<EXPR or x<=EXPR constraint */
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#define WHERE_BTM_LIMIT 0x00200000 /* x>EXPR or x>=EXPR constraint */
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#define WHERE_IDX_ONLY 0x00800000 /* Use index only - omit table */
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#define WHERE_ORDERBY 0x01000000 /* Output will appear in correct order */
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#define WHERE_REVERSE 0x02000000 /* Scan in reverse order */
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#define WHERE_UNIQUE 0x04000000 /* Selects no more than one row */
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#define WHERE_VIRTUALTABLE 0x08000000 /* Use virtual-table processing */
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#define WHERE_MULTI_OR 0x10000000 /* OR using multiple indices */
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/*
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** Initialize a preallocated WhereClause structure.
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*/
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static void whereClauseInit(
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WhereClause *pWC, /* The WhereClause to be initialized */
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Parse *pParse, /* The parsing context */
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WhereMaskSet *pMaskSet /* Mapping from table cursor numbers to bitmasks */
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){
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pWC->pParse = pParse;
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pWC->pMaskSet = pMaskSet;
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pWC->nTerm = 0;
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pWC->nSlot = ArraySize(pWC->aStatic);
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pWC->a = pWC->aStatic;
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pWC->vmask = 0;
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}
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/* Forward reference */
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static void whereClauseClear(WhereClause*);
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/*
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** Deallocate all memory associated with a WhereOrInfo object.
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*/
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static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){
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whereClauseClear(&p->wc);
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sqlite3DbFree(db, p);
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}
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/*
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** Deallocate all memory associated with a WhereAndInfo object.
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*/
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static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){
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whereClauseClear(&p->wc);
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sqlite3DbFree(db, p);
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}
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/*
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** Deallocate a WhereClause structure. The WhereClause structure
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** itself is not freed. This routine is the inverse of whereClauseInit().
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*/
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static void whereClauseClear(WhereClause *pWC){
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int i;
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WhereTerm *a;
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sqlite3 *db = pWC->pParse->db;
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for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
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if( a->wtFlags & TERM_DYNAMIC ){
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sqlite3ExprDelete(db, a->pExpr);
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}
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if( a->wtFlags & TERM_ORINFO ){
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whereOrInfoDelete(db, a->u.pOrInfo);
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}else if( a->wtFlags & TERM_ANDINFO ){
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whereAndInfoDelete(db, a->u.pAndInfo);
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}
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}
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if( pWC->a!=pWC->aStatic ){
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sqlite3DbFree(db, pWC->a);
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}
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}
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/*
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** Add a single new WhereTerm entry to the WhereClause object pWC.
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** The new WhereTerm object is constructed from Expr p and with wtFlags.
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** The index in pWC->a[] of the new WhereTerm is returned on success.
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** 0 is returned if the new WhereTerm could not be added due to a memory
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** allocation error. The memory allocation failure will be recorded in
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** the db->mallocFailed flag so that higher-level functions can detect it.
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**
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** This routine will increase the size of the pWC->a[] array as necessary.
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**
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** If the wtFlags argument includes TERM_DYNAMIC, then responsibility
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** for freeing the expression p is assumed by the WhereClause object pWC.
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** This is true even if this routine fails to allocate a new WhereTerm.
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**
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** WARNING: This routine might reallocate the space used to store
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** WhereTerms. All pointers to WhereTerms should be invalidated after
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** calling this routine. Such pointers may be reinitialized by referencing
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** the pWC->a[] array.
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*/
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static int whereClauseInsert(WhereClause *pWC, Expr *p, u8 wtFlags){
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WhereTerm *pTerm;
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int idx;
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if( pWC->nTerm>=pWC->nSlot ){
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WhereTerm *pOld = pWC->a;
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sqlite3 *db = pWC->pParse->db;
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pWC->a = sqlite3DbMallocRaw(db, sizeof(pWC->a[0])*pWC->nSlot*2 );
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if( pWC->a==0 ){
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if( wtFlags & TERM_DYNAMIC ){
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sqlite3ExprDelete(db, p);
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}
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pWC->a = pOld;
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return 0;
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}
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memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm);
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if( pOld!=pWC->aStatic ){
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sqlite3DbFree(db, pOld);
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}
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pWC->nSlot = sqlite3DbMallocSize(db, pWC->a)/sizeof(pWC->a[0]);
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}
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pTerm = &pWC->a[idx = pWC->nTerm++];
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pTerm->pExpr = p;
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pTerm->wtFlags = wtFlags;
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pTerm->pWC = pWC;
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pTerm->iParent = -1;
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return idx;
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}
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/*
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** This routine identifies subexpressions in the WHERE clause where
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** each subexpression is separated by the AND operator or some other
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** operator specified in the op parameter. The WhereClause structure
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** is filled with pointers to subexpressions. For example:
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**
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** WHERE a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
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** \________/ \_______________/ \________________/
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** slot[0] slot[1] slot[2]
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**
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** The original WHERE clause in pExpr is unaltered. All this routine
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** does is make slot[] entries point to substructure within pExpr.
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**
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** In the previous sentence and in the diagram, "slot[]" refers to
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** the WhereClause.a[] array. The slot[] array grows as needed to contain
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** all terms of the WHERE clause.
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*/
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static void whereSplit(WhereClause *pWC, Expr *pExpr, int op){
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pWC->op = (u8)op;
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if( pExpr==0 ) return;
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if( pExpr->op!=op ){
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whereClauseInsert(pWC, pExpr, 0);
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}else{
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whereSplit(pWC, pExpr->pLeft, op);
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whereSplit(pWC, pExpr->pRight, op);
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}
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}
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/*
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** Initialize an expression mask set (a WhereMaskSet object)
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*/
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#define initMaskSet(P) memset(P, 0, sizeof(*P))
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/*
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** Return the bitmask for the given cursor number. Return 0 if
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** iCursor is not in the set.
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*/
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static Bitmask getMask(WhereMaskSet *pMaskSet, int iCursor){
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int i;
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assert( pMaskSet->n<=sizeof(Bitmask)*8 );
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for(i=0; i<pMaskSet->n; i++){
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if( pMaskSet->ix[i]==iCursor ){
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return ((Bitmask)1)<<i;
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}
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}
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return 0;
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}
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|
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/*
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** Create a new mask for cursor iCursor.
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**
|
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** There is one cursor per table in the FROM clause. The number of
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** tables in the FROM clause is limited by a test early in the
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** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[]
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** array will never overflow.
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*/
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static void createMask(WhereMaskSet *pMaskSet, int iCursor){
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assert( pMaskSet->n < ArraySize(pMaskSet->ix) );
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pMaskSet->ix[pMaskSet->n++] = iCursor;
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}
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|
|
/*
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|
** This routine walks (recursively) an expression tree and generates
|
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** a bitmask indicating which tables are used in that expression
|
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** tree.
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**
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** In order for this routine to work, the calling function must have
|
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** previously invoked sqlite3ResolveExprNames() on the expression. See
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** the header comment on that routine for additional information.
|
|
** The sqlite3ResolveExprNames() routines looks for column names and
|
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** sets their opcodes to TK_COLUMN and their Expr.iTable fields to
|
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** the VDBE cursor number of the table. This routine just has to
|
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** translate the cursor numbers into bitmask values and OR all
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** the bitmasks together.
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*/
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|
static Bitmask exprListTableUsage(WhereMaskSet*, ExprList*);
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static Bitmask exprSelectTableUsage(WhereMaskSet*, Select*);
|
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static Bitmask exprTableUsage(WhereMaskSet *pMaskSet, Expr *p){
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Bitmask mask = 0;
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if( p==0 ) return 0;
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if( p->op==TK_COLUMN ){
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mask = getMask(pMaskSet, p->iTable);
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return mask;
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}
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mask = exprTableUsage(pMaskSet, p->pRight);
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mask |= exprTableUsage(pMaskSet, p->pLeft);
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if( ExprHasProperty(p, EP_xIsSelect) ){
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mask |= exprSelectTableUsage(pMaskSet, p->x.pSelect);
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}else{
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mask |= exprListTableUsage(pMaskSet, p->x.pList);
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}
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return mask;
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}
|
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static Bitmask exprListTableUsage(WhereMaskSet *pMaskSet, ExprList *pList){
|
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int i;
|
|
Bitmask mask = 0;
|
|
if( pList ){
|
|
for(i=0; i<pList->nExpr; i++){
|
|
mask |= exprTableUsage(pMaskSet, pList->a[i].pExpr);
|
|
}
|
|
}
|
|
return mask;
|
|
}
|
|
static Bitmask exprSelectTableUsage(WhereMaskSet *pMaskSet, Select *pS){
|
|
Bitmask mask = 0;
|
|
while( pS ){
|
|
mask |= exprListTableUsage(pMaskSet, pS->pEList);
|
|
mask |= exprListTableUsage(pMaskSet, pS->pGroupBy);
|
|
mask |= exprListTableUsage(pMaskSet, pS->pOrderBy);
|
|
mask |= exprTableUsage(pMaskSet, pS->pWhere);
|
|
mask |= exprTableUsage(pMaskSet, pS->pHaving);
|
|
pS = pS->pPrior;
|
|
}
|
|
return mask;
|
|
}
|
|
|
|
/*
|
|
** Return TRUE if the given operator is one of the operators that is
|
|
** allowed for an indexable WHERE clause term. The allowed operators are
|
|
** "=", "<", ">", "<=", ">=", and "IN".
|
|
*/
|
|
static int allowedOp(int op){
|
|
assert( TK_GT>TK_EQ && TK_GT<TK_GE );
|
|
assert( TK_LT>TK_EQ && TK_LT<TK_GE );
|
|
assert( TK_LE>TK_EQ && TK_LE<TK_GE );
|
|
assert( TK_GE==TK_EQ+4 );
|
|
return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL;
|
|
}
|
|
|
|
/*
|
|
** Swap two objects of type TYPE.
|
|
*/
|
|
#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
|
|
|
|
/*
|
|
** Commute a comparison operator. Expressions of the form "X op Y"
|
|
** are converted into "Y op X".
|
|
**
|
|
** If a collation sequence is associated with either the left or right
|
|
** side of the comparison, it remains associated with the same side after
|
|
** the commutation. So "Y collate NOCASE op X" becomes
|
|
** "X collate NOCASE op Y". This is because any collation sequence on
|
|
** the left hand side of a comparison overrides any collation sequence
|
|
** attached to the right. For the same reason the EP_ExpCollate flag
|
|
** is not commuted.
|
|
*/
|
|
static void exprCommute(Parse *pParse, Expr *pExpr){
|
|
u16 expRight = (pExpr->pRight->flags & EP_ExpCollate);
|
|
u16 expLeft = (pExpr->pLeft->flags & EP_ExpCollate);
|
|
assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
|
|
pExpr->pRight->pColl = sqlite3ExprCollSeq(pParse, pExpr->pRight);
|
|
pExpr->pLeft->pColl = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
|
|
SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl);
|
|
pExpr->pRight->flags = (pExpr->pRight->flags & ~EP_ExpCollate) | expLeft;
|
|
pExpr->pLeft->flags = (pExpr->pLeft->flags & ~EP_ExpCollate) | expRight;
|
|
SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
|
|
if( pExpr->op>=TK_GT ){
|
|
assert( TK_LT==TK_GT+2 );
|
|
assert( TK_GE==TK_LE+2 );
|
|
assert( TK_GT>TK_EQ );
|
|
assert( TK_GT<TK_LE );
|
|
assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
|
|
pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Translate from TK_xx operator to WO_xx bitmask.
|
|
*/
|
|
static u16 operatorMask(int op){
|
|
u16 c;
|
|
assert( allowedOp(op) );
|
|
if( op==TK_IN ){
|
|
c = WO_IN;
|
|
}else if( op==TK_ISNULL ){
|
|
c = WO_ISNULL;
|
|
}else{
|
|
assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff );
|
|
c = (u16)(WO_EQ<<(op-TK_EQ));
|
|
}
|
|
assert( op!=TK_ISNULL || c==WO_ISNULL );
|
|
assert( op!=TK_IN || c==WO_IN );
|
|
assert( op!=TK_EQ || c==WO_EQ );
|
|
assert( op!=TK_LT || c==WO_LT );
|
|
assert( op!=TK_LE || c==WO_LE );
|
|
assert( op!=TK_GT || c==WO_GT );
|
|
assert( op!=TK_GE || c==WO_GE );
|
|
return c;
|
|
}
|
|
|
|
/*
|
|
** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
|
|
** where X is a reference to the iColumn of table iCur and <op> is one of
|
|
** the WO_xx operator codes specified by the op parameter.
|
|
** Return a pointer to the term. Return 0 if not found.
|
|
*/
|
|
static WhereTerm *findTerm(
|
|
WhereClause *pWC, /* The WHERE clause to be searched */
|
|
int iCur, /* Cursor number of LHS */
|
|
int iColumn, /* Column number of LHS */
|
|
Bitmask notReady, /* RHS must not overlap with this mask */
|
|
u32 op, /* Mask of WO_xx values describing operator */
|
|
Index *pIdx /* Must be compatible with this index, if not NULL */
|
|
){
|
|
WhereTerm *pTerm;
|
|
int k;
|
|
assert( iCur>=0 );
|
|
op &= WO_ALL;
|
|
for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){
|
|
if( pTerm->leftCursor==iCur
|
|
&& (pTerm->prereqRight & notReady)==0
|
|
&& pTerm->u.leftColumn==iColumn
|
|
&& (pTerm->eOperator & op)!=0
|
|
){
|
|
if( pIdx && pTerm->eOperator!=WO_ISNULL ){
|
|
Expr *pX = pTerm->pExpr;
|
|
CollSeq *pColl;
|
|
char idxaff;
|
|
int j;
|
|
Parse *pParse = pWC->pParse;
|
|
|
|
idxaff = pIdx->pTable->aCol[iColumn].affinity;
|
|
if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue;
|
|
|
|
/* Figure out the collation sequence required from an index for
|
|
** it to be useful for optimising expression pX. Store this
|
|
** value in variable pColl.
|
|
*/
|
|
assert(pX->pLeft);
|
|
pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight);
|
|
assert(pColl || pParse->nErr);
|
|
|
|
for(j=0; pIdx->aiColumn[j]!=iColumn; j++){
|
|
if( NEVER(j>=pIdx->nColumn) ) return 0;
|
|
}
|
|
if( pColl && sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ) continue;
|
|
}
|
|
return pTerm;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Forward reference */
|
|
static void exprAnalyze(SrcList*, WhereClause*, int);
|
|
|
|
/*
|
|
** Call exprAnalyze on all terms in a WHERE clause.
|
|
**
|
|
**
|
|
*/
|
|
static void exprAnalyzeAll(
|
|
SrcList *pTabList, /* the FROM clause */
|
|
WhereClause *pWC /* the WHERE clause to be analyzed */
|
|
){
|
|
int i;
|
|
for(i=pWC->nTerm-1; i>=0; i--){
|
|
exprAnalyze(pTabList, pWC, i);
|
|
}
|
|
}
|
|
|
|
#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
|
|
/*
|
|
** Check to see if the given expression is a LIKE or GLOB operator that
|
|
** can be optimized using inequality constraints. Return TRUE if it is
|
|
** so and false if not.
|
|
**
|
|
** In order for the operator to be optimizible, the RHS must be a string
|
|
** literal that does not begin with a wildcard.
|
|
*/
|
|
static int isLikeOrGlob(
|
|
Parse *pParse, /* Parsing and code generating context */
|
|
Expr *pExpr, /* Test this expression */
|
|
int *pnPattern, /* Number of non-wildcard prefix characters */
|
|
int *pisComplete, /* True if the only wildcard is % in the last character */
|
|
int *pnoCase /* True if uppercase is equivalent to lowercase */
|
|
){
|
|
const char *z; /* String on RHS of LIKE operator */
|
|
Expr *pRight, *pLeft; /* Right and left size of LIKE operator */
|
|
ExprList *pList; /* List of operands to the LIKE operator */
|
|
int c; /* One character in z[] */
|
|
int cnt; /* Number of non-wildcard prefix characters */
|
|
char wc[3]; /* Wildcard characters */
|
|
CollSeq *pColl; /* Collating sequence for LHS */
|
|
sqlite3 *db = pParse->db; /* Database connection */
|
|
|
|
if( !sqlite3IsLikeFunction(db, pExpr, pnoCase, wc) ){
|
|
return 0;
|
|
}
|
|
#ifdef SQLITE_EBCDIC
|
|
if( *pnoCase ) return 0;
|
|
#endif
|
|
pList = pExpr->x.pList;
|
|
pRight = pList->a[0].pExpr;
|
|
if( pRight->op!=TK_STRING ){
|
|
return 0;
|
|
}
|
|
pLeft = pList->a[1].pExpr;
|
|
if( pLeft->op!=TK_COLUMN ){
|
|
return 0;
|
|
}
|
|
pColl = sqlite3ExprCollSeq(pParse, pLeft);
|
|
assert( pColl!=0 || pLeft->iColumn==-1 );
|
|
if( pColl==0 ){
|
|
/* No collation is defined for the ROWID. Use the default. */
|
|
pColl = db->pDfltColl;
|
|
}
|
|
if( (pColl->type!=SQLITE_COLL_BINARY || *pnoCase) &&
|
|
(pColl->type!=SQLITE_COLL_NOCASE || !*pnoCase) ){
|
|
return 0;
|
|
}
|
|
z = pRight->u.zToken;
|
|
cnt = 0;
|
|
if( z ){
|
|
while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){
|
|
cnt++;
|
|
}
|
|
}
|
|
if( cnt==0 || c==0 || 255==(u8)z[cnt-1] ){
|
|
return 0;
|
|
}
|
|
*pisComplete = z[cnt]==wc[0] && z[cnt+1]==0;
|
|
*pnPattern = cnt;
|
|
return 1;
|
|
}
|
|
#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
|
|
|
|
|
|
#ifndef SQLITE_OMIT_VIRTUALTABLE
|
|
/*
|
|
** Check to see if the given expression is of the form
|
|
**
|
|
** column MATCH expr
|
|
**
|
|
** If it is then return TRUE. If not, return FALSE.
|
|
*/
|
|
static int isMatchOfColumn(
|
|
Expr *pExpr /* Test this expression */
|
|
){
|
|
ExprList *pList;
|
|
|
|
if( pExpr->op!=TK_FUNCTION ){
|
|
return 0;
|
|
}
|
|
if( sqlite3StrICmp(pExpr->u.zToken,"match")!=0 ){
|
|
return 0;
|
|
}
|
|
pList = pExpr->x.pList;
|
|
if( pList->nExpr!=2 ){
|
|
return 0;
|
|
}
|
|
if( pList->a[1].pExpr->op != TK_COLUMN ){
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
#endif /* SQLITE_OMIT_VIRTUALTABLE */
|
|
|
|
/*
|
|
** If the pBase expression originated in the ON or USING clause of
|
|
** a join, then transfer the appropriate markings over to derived.
|
|
*/
|
|
static void transferJoinMarkings(Expr *pDerived, Expr *pBase){
|
|
pDerived->flags |= pBase->flags & EP_FromJoin;
|
|
pDerived->iRightJoinTable = pBase->iRightJoinTable;
|
|
}
|
|
|
|
#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
|
|
/*
|
|
** Analyze a term that consists of two or more OR-connected
|
|
** subterms. So in:
|
|
**
|
|
** ... WHERE (a=5) AND (b=7 OR c=9 OR d=13) AND (d=13)
|
|
** ^^^^^^^^^^^^^^^^^^^^
|
|
**
|
|
** This routine analyzes terms such as the middle term in the above example.
|
|
** A WhereOrTerm object is computed and attached to the term under
|
|
** analysis, regardless of the outcome of the analysis. Hence:
|
|
**
|
|
** WhereTerm.wtFlags |= TERM_ORINFO
|
|
** WhereTerm.u.pOrInfo = a dynamically allocated WhereOrTerm object
|
|
**
|
|
** The term being analyzed must have two or more of OR-connected subterms.
|
|
** A single subterm might be a set of AND-connected sub-subterms.
|
|
** Examples of terms under analysis:
|
|
**
|
|
** (A) t1.x=t2.y OR t1.x=t2.z OR t1.y=15 OR t1.z=t3.a+5
|
|
** (B) x=expr1 OR expr2=x OR x=expr3
|
|
** (C) t1.x=t2.y OR (t1.x=t2.z AND t1.y=15)
|
|
** (D) x=expr1 OR (y>11 AND y<22 AND z LIKE '*hello*')
|
|
** (E) (p.a=1 AND q.b=2 AND r.c=3) OR (p.x=4 AND q.y=5 AND r.z=6)
|
|
**
|
|
** CASE 1:
|
|
**
|
|
** If all subterms are of the form T.C=expr for some single column of C
|
|
** a single table T (as shown in example B above) then create a new virtual
|
|
** term that is an equivalent IN expression. In other words, if the term
|
|
** being analyzed is:
|
|
**
|
|
** x = expr1 OR expr2 = x OR x = expr3
|
|
**
|
|
** then create a new virtual term like this:
|
|
**
|
|
** x IN (expr1,expr2,expr3)
|
|
**
|
|
** CASE 2:
|
|
**
|
|
** If all subterms are indexable by a single table T, then set
|
|
**
|
|
** WhereTerm.eOperator = WO_OR
|
|
** WhereTerm.u.pOrInfo->indexable |= the cursor number for table T
|
|
**
|
|
** A subterm is "indexable" if it is of the form
|
|
** "T.C <op> <expr>" where C is any column of table T and
|
|
** <op> is one of "=", "<", "<=", ">", ">=", "IS NULL", or "IN".
|
|
** A subterm is also indexable if it is an AND of two or more
|
|
** subsubterms at least one of which is indexable. Indexable AND
|
|
** subterms have their eOperator set to WO_AND and they have
|
|
** u.pAndInfo set to a dynamically allocated WhereAndTerm object.
|
|
**
|
|
** From another point of view, "indexable" means that the subterm could
|
|
** potentially be used with an index if an appropriate index exists.
|
|
** This analysis does not consider whether or not the index exists; that
|
|
** is something the bestIndex() routine will determine. This analysis
|
|
** only looks at whether subterms appropriate for indexing exist.
|
|
**
|
|
** All examples A through E above all satisfy case 2. But if a term
|
|
** also statisfies case 1 (such as B) we know that the optimizer will
|
|
** always prefer case 1, so in that case we pretend that case 2 is not
|
|
** satisfied.
|
|
**
|
|
** It might be the case that multiple tables are indexable. For example,
|
|
** (E) above is indexable on tables P, Q, and R.
|
|
**
|
|
** Terms that satisfy case 2 are candidates for lookup by using
|
|
** separate indices to find rowids for each subterm and composing
|
|
** the union of all rowids using a RowSet object. This is similar
|
|
** to "bitmap indices" in other database engines.
|
|
**
|
|
** OTHERWISE:
|
|
**
|
|
** If neither case 1 nor case 2 apply, then leave the eOperator set to
|
|
** zero. This term is not useful for search.
|
|
*/
|
|
static void exprAnalyzeOrTerm(
|
|
SrcList *pSrc, /* the FROM clause */
|
|
WhereClause *pWC, /* the complete WHERE clause */
|
|
int idxTerm /* Index of the OR-term to be analyzed */
|
|
){
|
|
Parse *pParse = pWC->pParse; /* Parser context */
|
|
sqlite3 *db = pParse->db; /* Database connection */
|
|
WhereTerm *pTerm = &pWC->a[idxTerm]; /* The term to be analyzed */
|
|
Expr *pExpr = pTerm->pExpr; /* The expression of the term */
|
|
WhereMaskSet *pMaskSet = pWC->pMaskSet; /* Table use masks */
|
|
int i; /* Loop counters */
|
|
WhereClause *pOrWc; /* Breakup of pTerm into subterms */
|
|
WhereTerm *pOrTerm; /* A Sub-term within the pOrWc */
|
|
WhereOrInfo *pOrInfo; /* Additional information associated with pTerm */
|
|
Bitmask chngToIN; /* Tables that might satisfy case 1 */
|
|
Bitmask indexable; /* Tables that are indexable, satisfying case 2 */
|
|
|
|
/*
|
|
** Break the OR clause into its separate subterms. The subterms are
|
|
** stored in a WhereClause structure containing within the WhereOrInfo
|
|
** object that is attached to the original OR clause term.
|
|
*/
|
|
assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
|
|
assert( pExpr->op==TK_OR );
|
|
pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
|
|
if( pOrInfo==0 ) return;
|
|
pTerm->wtFlags |= TERM_ORINFO;
|
|
pOrWc = &pOrInfo->wc;
|
|
whereClauseInit(pOrWc, pWC->pParse, pMaskSet);
|
|
whereSplit(pOrWc, pExpr, TK_OR);
|
|
exprAnalyzeAll(pSrc, pOrWc);
|
|
if( db->mallocFailed ) return;
|
|
assert( pOrWc->nTerm>=2 );
|
|
|
|
/*
|
|
** Compute the set of tables that might satisfy cases 1 or 2.
|
|
*/
|
|
indexable = ~(Bitmask)0;
|
|
chngToIN = ~(pWC->vmask);
|
|
for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){
|
|
if( (pOrTerm->eOperator & WO_SINGLE)==0 ){
|
|
WhereAndInfo *pAndInfo;
|
|
assert( pOrTerm->eOperator==0 );
|
|
assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 );
|
|
chngToIN = 0;
|
|
pAndInfo = sqlite3DbMallocRaw(db, sizeof(*pAndInfo));
|
|
if( pAndInfo ){
|
|
WhereClause *pAndWC;
|
|
WhereTerm *pAndTerm;
|
|
int j;
|
|
Bitmask b = 0;
|
|
pOrTerm->u.pAndInfo = pAndInfo;
|
|
pOrTerm->wtFlags |= TERM_ANDINFO;
|
|
pOrTerm->eOperator = WO_AND;
|
|
pAndWC = &pAndInfo->wc;
|
|
whereClauseInit(pAndWC, pWC->pParse, pMaskSet);
|
|
whereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
|
|
exprAnalyzeAll(pSrc, pAndWC);
|
|
testcase( db->mallocFailed );
|
|
if( !db->mallocFailed ){
|
|
for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
|
|
assert( pAndTerm->pExpr );
|
|
if( allowedOp(pAndTerm->pExpr->op) ){
|
|
b |= getMask(pMaskSet, pAndTerm->leftCursor);
|
|
}
|
|
}
|
|
}
|
|
indexable &= b;
|
|
}
|
|
}else if( pOrTerm->wtFlags & TERM_COPIED ){
|
|
/* Skip this term for now. We revisit it when we process the
|
|
** corresponding TERM_VIRTUAL term */
|
|
}else{
|
|
Bitmask b;
|
|
b = getMask(pMaskSet, pOrTerm->leftCursor);
|
|
if( pOrTerm->wtFlags & TERM_VIRTUAL ){
|
|
WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent];
|
|
b |= getMask(pMaskSet, pOther->leftCursor);
|
|
}
|
|
indexable &= b;
|
|
if( pOrTerm->eOperator!=WO_EQ ){
|
|
chngToIN = 0;
|
|
}else{
|
|
chngToIN &= b;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Record the set of tables that satisfy case 2. The set might be
|
|
** empty.
|
|
*/
|
|
pOrInfo->indexable = indexable;
|
|
pTerm->eOperator = indexable==0 ? 0 : WO_OR;
|
|
|
|
/*
|
|
** chngToIN holds a set of tables that *might* satisfy case 1. But
|
|
** we have to do some additional checking to see if case 1 really
|
|
** is satisfied.
|
|
*/
|
|
if( chngToIN ){
|
|
int okToChngToIN = 0; /* True if the conversion to IN is valid */
|
|
int iColumn = -1; /* Column index on lhs of IN operator */
|
|
int iCursor = -1; /* Table cursor common to all terms */
|
|
int j = 0; /* Loop counter */
|
|
|
|
/* Search for a table and column that appears on one side or the
|
|
** other of the == operator in every subterm. That table and column
|
|
** will be recorded in iCursor and iColumn. There might not be any
|
|
** such table and column. Set okToChngToIN if an appropriate table
|
|
** and column is found but leave okToChngToIN false if not found.
|
|
*/
|
|
for(j=0; j<2 && !okToChngToIN; j++){
|
|
pOrTerm = pOrWc->a;
|
|
for(i=pOrWc->nTerm-1; i>=0; i--, pOrTerm++){
|
|
assert( pOrTerm->eOperator==WO_EQ );
|
|
pOrTerm->wtFlags &= ~TERM_OR_OK;
|
|
if( pOrTerm->leftCursor==iColumn ) continue;
|
|
if( (chngToIN & getMask(pMaskSet, pOrTerm->leftCursor))==0 ) continue;
|
|
iColumn = pOrTerm->u.leftColumn;
|
|
iCursor = pOrTerm->leftCursor;
|
|
break;
|
|
}
|
|
if( i<0 ){
|
|
assert( j==1 );
|
|
assert( (chngToIN&(chngToIN-1))==0 );
|
|
assert( chngToIN==getMask(pMaskSet, iColumn) );
|
|
break;
|
|
}
|
|
okToChngToIN = 1;
|
|
for(; i>=0 && okToChngToIN; i--, pOrTerm++){
|
|
assert( pOrTerm->eOperator==WO_EQ );
|
|
if( pOrTerm->leftCursor!=iCursor ){
|
|
pOrTerm->wtFlags &= ~TERM_OR_OK;
|
|
}else if( pOrTerm->u.leftColumn!=iColumn ){
|
|
okToChngToIN = 0;
|
|
}else{
|
|
int affLeft, affRight;
|
|
/* If the right-hand side is also a column, then the affinities
|
|
** of both right and left sides must be such that no type
|
|
** conversions are required on the right. (Ticket #2249)
|
|
*/
|
|
affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight);
|
|
affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft);
|
|
if( affRight!=0 && affRight!=affLeft ){
|
|
okToChngToIN = 0;
|
|
}else{
|
|
pOrTerm->wtFlags |= TERM_OR_OK;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* At this point, okToChngToIN is true if original pTerm satisfies
|
|
** case 1. In that case, construct a new virtual term that is
|
|
** pTerm converted into an IN operator.
|
|
*/
|
|
if( okToChngToIN ){
|
|
Expr *pDup; /* A transient duplicate expression */
|
|
ExprList *pList = 0; /* The RHS of the IN operator */
|
|
Expr *pLeft = 0; /* The LHS of the IN operator */
|
|
Expr *pNew; /* The complete IN operator */
|
|
|
|
for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0; i--, pOrTerm++){
|
|
if( (pOrTerm->wtFlags & TERM_OR_OK)==0 ) continue;
|
|
assert( pOrTerm->eOperator==WO_EQ );
|
|
assert( pOrTerm->leftCursor==iCursor );
|
|
assert( pOrTerm->u.leftColumn==iColumn );
|
|
pDup = sqlite3ExprDup(db, pOrTerm->pExpr->pRight, 0);
|
|
pList = sqlite3ExprListAppend(pWC->pParse, pList, pDup);
|
|
pLeft = pOrTerm->pExpr->pLeft;
|
|
}
|
|
assert( pLeft!=0 );
|
|
pDup = sqlite3ExprDup(db, pLeft, 0);
|
|
pNew = sqlite3PExpr(pParse, TK_IN, pDup, 0, 0);
|
|
if( pNew ){
|
|
int idxNew;
|
|
transferJoinMarkings(pNew, pExpr);
|
|
assert( !ExprHasProperty(pNew, EP_xIsSelect) );
|
|
pNew->x.pList = pList;
|
|
idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
testcase( idxNew==0 );
|
|
exprAnalyze(pSrc, pWC, idxNew);
|
|
pTerm = &pWC->a[idxTerm];
|
|
pWC->a[idxNew].iParent = idxTerm;
|
|
pTerm->nChild = 1;
|
|
}else{
|
|
sqlite3ExprListDelete(db, pList);
|
|
}
|
|
pTerm->eOperator = 0; /* case 1 trumps case 2 */
|
|
}
|
|
}
|
|
}
|
|
#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */
|
|
|
|
|
|
/*
|
|
** The input to this routine is an WhereTerm structure with only the
|
|
** "pExpr" field filled in. The job of this routine is to analyze the
|
|
** subexpression and populate all the other fields of the WhereTerm
|
|
** structure.
|
|
**
|
|
** If the expression is of the form "<expr> <op> X" it gets commuted
|
|
** to the standard form of "X <op> <expr>".
|
|
**
|
|
** If the expression is of the form "X <op> Y" where both X and Y are
|
|
** columns, then the original expression is unchanged and a new virtual
|
|
** term of the form "Y <op> X" is added to the WHERE clause and
|
|
** analyzed separately. The original term is marked with TERM_COPIED
|
|
** and the new term is marked with TERM_DYNAMIC (because it's pExpr
|
|
** needs to be freed with the WhereClause) and TERM_VIRTUAL (because it
|
|
** is a commuted copy of a prior term.) The original term has nChild=1
|
|
** and the copy has idxParent set to the index of the original term.
|
|
*/
|
|
static void exprAnalyze(
|
|
SrcList *pSrc, /* the FROM clause */
|
|
WhereClause *pWC, /* the WHERE clause */
|
|
int idxTerm /* Index of the term to be analyzed */
|
|
){
|
|
WhereTerm *pTerm; /* The term to be analyzed */
|
|
WhereMaskSet *pMaskSet; /* Set of table index masks */
|
|
Expr *pExpr; /* The expression to be analyzed */
|
|
Bitmask prereqLeft; /* Prerequesites of the pExpr->pLeft */
|
|
Bitmask prereqAll; /* Prerequesites of pExpr */
|
|
Bitmask extraRight = 0;
|
|
int nPattern;
|
|
int isComplete;
|
|
int noCase;
|
|
int op; /* Top-level operator. pExpr->op */
|
|
Parse *pParse = pWC->pParse; /* Parsing context */
|
|
sqlite3 *db = pParse->db; /* Database connection */
|
|
|
|
if( db->mallocFailed ){
|
|
return;
|
|
}
|
|
pTerm = &pWC->a[idxTerm];
|
|
pMaskSet = pWC->pMaskSet;
|
|
pExpr = pTerm->pExpr;
|
|
prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft);
|
|
op = pExpr->op;
|
|
if( op==TK_IN ){
|
|
assert( pExpr->pRight==0 );
|
|
if( ExprHasProperty(pExpr, EP_xIsSelect) ){
|
|
pTerm->prereqRight = exprSelectTableUsage(pMaskSet, pExpr->x.pSelect);
|
|
}else{
|
|
pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->x.pList);
|
|
}
|
|
}else if( op==TK_ISNULL ){
|
|
pTerm->prereqRight = 0;
|
|
}else{
|
|
pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight);
|
|
}
|
|
prereqAll = exprTableUsage(pMaskSet, pExpr);
|
|
if( ExprHasProperty(pExpr, EP_FromJoin) ){
|
|
Bitmask x = getMask(pMaskSet, pExpr->iRightJoinTable);
|
|
prereqAll |= x;
|
|
extraRight = x-1; /* ON clause terms may not be used with an index
|
|
** on left table of a LEFT JOIN. Ticket #3015 */
|
|
}
|
|
pTerm->prereqAll = prereqAll;
|
|
pTerm->leftCursor = -1;
|
|
pTerm->iParent = -1;
|
|
pTerm->eOperator = 0;
|
|
if( allowedOp(op) && (pTerm->prereqRight & prereqLeft)==0 ){
|
|
Expr *pLeft = pExpr->pLeft;
|
|
Expr *pRight = pExpr->pRight;
|
|
if( pLeft->op==TK_COLUMN ){
|
|
pTerm->leftCursor = pLeft->iTable;
|
|
pTerm->u.leftColumn = pLeft->iColumn;
|
|
pTerm->eOperator = operatorMask(op);
|
|
}
|
|
if( pRight && pRight->op==TK_COLUMN ){
|
|
WhereTerm *pNew;
|
|
Expr *pDup;
|
|
if( pTerm->leftCursor>=0 ){
|
|
int idxNew;
|
|
pDup = sqlite3ExprDup(db, pExpr, 0);
|
|
if( db->mallocFailed ){
|
|
sqlite3ExprDelete(db, pDup);
|
|
return;
|
|
}
|
|
idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
if( idxNew==0 ) return;
|
|
pNew = &pWC->a[idxNew];
|
|
pNew->iParent = idxTerm;
|
|
pTerm = &pWC->a[idxTerm];
|
|
pTerm->nChild = 1;
|
|
pTerm->wtFlags |= TERM_COPIED;
|
|
}else{
|
|
pDup = pExpr;
|
|
pNew = pTerm;
|
|
}
|
|
exprCommute(pParse, pDup);
|
|
pLeft = pDup->pLeft;
|
|
pNew->leftCursor = pLeft->iTable;
|
|
pNew->u.leftColumn = pLeft->iColumn;
|
|
pNew->prereqRight = prereqLeft;
|
|
pNew->prereqAll = prereqAll;
|
|
pNew->eOperator = operatorMask(pDup->op);
|
|
}
|
|
}
|
|
|
|
#ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION
|
|
/* If a term is the BETWEEN operator, create two new virtual terms
|
|
** that define the range that the BETWEEN implements. For example:
|
|
**
|
|
** a BETWEEN b AND c
|
|
**
|
|
** is converted into:
|
|
**
|
|
** (a BETWEEN b AND c) AND (a>=b) AND (a<=c)
|
|
**
|
|
** The two new terms are added onto the end of the WhereClause object.
|
|
** The new terms are "dynamic" and are children of the original BETWEEN
|
|
** term. That means that if the BETWEEN term is coded, the children are
|
|
** skipped. Or, if the children are satisfied by an index, the original
|
|
** BETWEEN term is skipped.
|
|
*/
|
|
else if( pExpr->op==TK_BETWEEN && pWC->op==TK_AND ){
|
|
ExprList *pList = pExpr->x.pList;
|
|
int i;
|
|
static const u8 ops[] = {TK_GE, TK_LE};
|
|
assert( pList!=0 );
|
|
assert( pList->nExpr==2 );
|
|
for(i=0; i<2; i++){
|
|
Expr *pNewExpr;
|
|
int idxNew;
|
|
pNewExpr = sqlite3PExpr(pParse, ops[i],
|
|
sqlite3ExprDup(db, pExpr->pLeft, 0),
|
|
sqlite3ExprDup(db, pList->a[i].pExpr, 0), 0);
|
|
idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
testcase( idxNew==0 );
|
|
exprAnalyze(pSrc, pWC, idxNew);
|
|
pTerm = &pWC->a[idxTerm];
|
|
pWC->a[idxNew].iParent = idxTerm;
|
|
}
|
|
pTerm->nChild = 2;
|
|
}
|
|
#endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */
|
|
|
|
#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
|
|
/* Analyze a term that is composed of two or more subterms connected by
|
|
** an OR operator.
|
|
*/
|
|
else if( pExpr->op==TK_OR ){
|
|
assert( pWC->op==TK_AND );
|
|
exprAnalyzeOrTerm(pSrc, pWC, idxTerm);
|
|
}
|
|
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
|
|
|
|
#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
|
|
/* Add constraints to reduce the search space on a LIKE or GLOB
|
|
** operator.
|
|
**
|
|
** A like pattern of the form "x LIKE 'abc%'" is changed into constraints
|
|
**
|
|
** x>='abc' AND x<'abd' AND x LIKE 'abc%'
|
|
**
|
|
** The last character of the prefix "abc" is incremented to form the
|
|
** termination condition "abd".
|
|
*/
|
|
if( isLikeOrGlob(pParse, pExpr, &nPattern, &isComplete, &noCase)
|
|
&& pWC->op==TK_AND ){
|
|
Expr *pLeft, *pRight;
|
|
Expr *pStr1, *pStr2;
|
|
Expr *pNewExpr1, *pNewExpr2;
|
|
int idxNew1, idxNew2;
|
|
|
|
pLeft = pExpr->x.pList->a[1].pExpr;
|
|
pRight = pExpr->x.pList->a[0].pExpr;
|
|
pStr1 = sqlite3Expr(db, TK_STRING, pRight->u.zToken);
|
|
if( pStr1 ) pStr1->u.zToken[nPattern] = 0;
|
|
pStr2 = sqlite3ExprDup(db, pStr1, 0);
|
|
if( !db->mallocFailed ){
|
|
u8 c, *pC;
|
|
pC = (u8*)&pStr2->u.zToken[nPattern-1];
|
|
c = *pC;
|
|
if( noCase ){
|
|
if( c=='@' ) isComplete = 0;
|
|
c = sqlite3UpperToLower[c];
|
|
}
|
|
*pC = c + 1;
|
|
}
|
|
pNewExpr1 = sqlite3PExpr(pParse, TK_GE, sqlite3ExprDup(db,pLeft,0),pStr1,0);
|
|
idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
testcase( idxNew1==0 );
|
|
exprAnalyze(pSrc, pWC, idxNew1);
|
|
pNewExpr2 = sqlite3PExpr(pParse, TK_LT, sqlite3ExprDup(db,pLeft,0),pStr2,0);
|
|
idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
testcase( idxNew2==0 );
|
|
exprAnalyze(pSrc, pWC, idxNew2);
|
|
pTerm = &pWC->a[idxTerm];
|
|
if( isComplete ){
|
|
pWC->a[idxNew1].iParent = idxTerm;
|
|
pWC->a[idxNew2].iParent = idxTerm;
|
|
pTerm->nChild = 2;
|
|
}
|
|
}
|
|
#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
|
|
|
|
#ifndef SQLITE_OMIT_VIRTUALTABLE
|
|
/* Add a WO_MATCH auxiliary term to the constraint set if the
|
|
** current expression is of the form: column MATCH expr.
|
|
** This information is used by the xBestIndex methods of
|
|
** virtual tables. The native query optimizer does not attempt
|
|
** to do anything with MATCH functions.
|
|
*/
|
|
if( isMatchOfColumn(pExpr) ){
|
|
int idxNew;
|
|
Expr *pRight, *pLeft;
|
|
WhereTerm *pNewTerm;
|
|
Bitmask prereqColumn, prereqExpr;
|
|
|
|
pRight = pExpr->x.pList->a[0].pExpr;
|
|
pLeft = pExpr->x.pList->a[1].pExpr;
|
|
prereqExpr = exprTableUsage(pMaskSet, pRight);
|
|
prereqColumn = exprTableUsage(pMaskSet, pLeft);
|
|
if( (prereqExpr & prereqColumn)==0 ){
|
|
Expr *pNewExpr;
|
|
pNewExpr = sqlite3PExpr(pParse, TK_MATCH,
|
|
0, sqlite3ExprDup(db, pRight, 0), 0);
|
|
idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
testcase( idxNew==0 );
|
|
pNewTerm = &pWC->a[idxNew];
|
|
pNewTerm->prereqRight = prereqExpr;
|
|
pNewTerm->leftCursor = pLeft->iTable;
|
|
pNewTerm->u.leftColumn = pLeft->iColumn;
|
|
pNewTerm->eOperator = WO_MATCH;
|
|
pNewTerm->iParent = idxTerm;
|
|
pTerm = &pWC->a[idxTerm];
|
|
pTerm->nChild = 1;
|
|
pTerm->wtFlags |= TERM_COPIED;
|
|
pNewTerm->prereqAll = pTerm->prereqAll;
|
|
}
|
|
}
|
|
#endif /* SQLITE_OMIT_VIRTUALTABLE */
|
|
|
|
/* Prevent ON clause terms of a LEFT JOIN from being used to drive
|
|
** an index for tables to the left of the join.
|
|
*/
|
|
pTerm->prereqRight |= extraRight;
|
|
}
|
|
|
|
/*
|
|
** Return TRUE if any of the expressions in pList->a[iFirst...] contain
|
|
** a reference to any table other than the iBase table.
|
|
*/
|
|
static int referencesOtherTables(
|
|
ExprList *pList, /* Search expressions in ths list */
|
|
WhereMaskSet *pMaskSet, /* Mapping from tables to bitmaps */
|
|
int iFirst, /* Be searching with the iFirst-th expression */
|
|
int iBase /* Ignore references to this table */
|
|
){
|
|
Bitmask allowed = ~getMask(pMaskSet, iBase);
|
|
while( iFirst<pList->nExpr ){
|
|
if( (exprTableUsage(pMaskSet, pList->a[iFirst++].pExpr)&allowed)!=0 ){
|
|
return 1;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
** This routine decides if pIdx can be used to satisfy the ORDER BY
|
|
** clause. If it can, it returns 1. If pIdx cannot satisfy the
|
|
** ORDER BY clause, this routine returns 0.
|
|
**
|
|
** pOrderBy is an ORDER BY clause from a SELECT statement. pTab is the
|
|
** left-most table in the FROM clause of that same SELECT statement and
|
|
** the table has a cursor number of "base". pIdx is an index on pTab.
|
|
**
|
|
** nEqCol is the number of columns of pIdx that are used as equality
|
|
** constraints. Any of these columns may be missing from the ORDER BY
|
|
** clause and the match can still be a success.
|
|
**
|
|
** All terms of the ORDER BY that match against the index must be either
|
|
** ASC or DESC. (Terms of the ORDER BY clause past the end of a UNIQUE
|
|
** index do not need to satisfy this constraint.) The *pbRev value is
|
|
** set to 1 if the ORDER BY clause is all DESC and it is set to 0 if
|
|
** the ORDER BY clause is all ASC.
|
|
*/
|
|
static int isSortingIndex(
|
|
Parse *pParse, /* Parsing context */
|
|
WhereMaskSet *pMaskSet, /* Mapping from table cursor numbers to bitmaps */
|
|
Index *pIdx, /* The index we are testing */
|
|
int base, /* Cursor number for the table to be sorted */
|
|
ExprList *pOrderBy, /* The ORDER BY clause */
|
|
int nEqCol, /* Number of index columns with == constraints */
|
|
int *pbRev /* Set to 1 if ORDER BY is DESC */
|
|
){
|
|
int i, j; /* Loop counters */
|
|
int sortOrder = 0; /* XOR of index and ORDER BY sort direction */
|
|
int nTerm; /* Number of ORDER BY terms */
|
|
struct ExprList_item *pTerm; /* A term of the ORDER BY clause */
|
|
sqlite3 *db = pParse->db;
|
|
|
|
assert( pOrderBy!=0 );
|
|
nTerm = pOrderBy->nExpr;
|
|
assert( nTerm>0 );
|
|
|
|
/* Match terms of the ORDER BY clause against columns of
|
|
** the index.
|
|
**
|
|
** Note that indices have pIdx->nColumn regular columns plus
|
|
** one additional column containing the rowid. The rowid column
|
|
** of the index is also allowed to match against the ORDER BY
|
|
** clause.
|
|
*/
|
|
for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<=pIdx->nColumn; i++){
|
|
Expr *pExpr; /* The expression of the ORDER BY pTerm */
|
|
CollSeq *pColl; /* The collating sequence of pExpr */
|
|
int termSortOrder; /* Sort order for this term */
|
|
int iColumn; /* The i-th column of the index. -1 for rowid */
|
|
int iSortOrder; /* 1 for DESC, 0 for ASC on the i-th index term */
|
|
const char *zColl; /* Name of the collating sequence for i-th index term */
|
|
|
|
pExpr = pTerm->pExpr;
|
|
if( pExpr->op!=TK_COLUMN || pExpr->iTable!=base ){
|
|
/* Can not use an index sort on anything that is not a column in the
|
|
** left-most table of the FROM clause */
|
|
break;
|
|
}
|
|
pColl = sqlite3ExprCollSeq(pParse, pExpr);
|
|
if( !pColl ){
|
|
pColl = db->pDfltColl;
|
|
}
|
|
if( i<pIdx->nColumn ){
|
|
iColumn = pIdx->aiColumn[i];
|
|
if( iColumn==pIdx->pTable->iPKey ){
|
|
iColumn = -1;
|
|
}
|
|
iSortOrder = pIdx->aSortOrder[i];
|
|
zColl = pIdx->azColl[i];
|
|
}else{
|
|
iColumn = -1;
|
|
iSortOrder = 0;
|
|
zColl = pColl->zName;
|
|
}
|
|
if( pExpr->iColumn!=iColumn || sqlite3StrICmp(pColl->zName, zColl) ){
|
|
/* Term j of the ORDER BY clause does not match column i of the index */
|
|
if( i<nEqCol ){
|
|
/* If an index column that is constrained by == fails to match an
|
|
** ORDER BY term, that is OK. Just ignore that column of the index
|
|
*/
|
|
continue;
|
|
}else if( i==pIdx->nColumn ){
|
|
/* Index column i is the rowid. All other terms match. */
|
|
break;
|
|
}else{
|
|
/* If an index column fails to match and is not constrained by ==
|
|
** then the index cannot satisfy the ORDER BY constraint.
|
|
*/
|
|
return 0;
|
|
}
|
|
}
|
|
assert( pIdx->aSortOrder!=0 );
|
|
assert( pTerm->sortOrder==0 || pTerm->sortOrder==1 );
|
|
assert( iSortOrder==0 || iSortOrder==1 );
|
|
termSortOrder = iSortOrder ^ pTerm->sortOrder;
|
|
if( i>nEqCol ){
|
|
if( termSortOrder!=sortOrder ){
|
|
/* Indices can only be used if all ORDER BY terms past the
|
|
** equality constraints are all either DESC or ASC. */
|
|
return 0;
|
|
}
|
|
}else{
|
|
sortOrder = termSortOrder;
|
|
}
|
|
j++;
|
|
pTerm++;
|
|
if( iColumn<0 && !referencesOtherTables(pOrderBy, pMaskSet, j, base) ){
|
|
/* If the indexed column is the primary key and everything matches
|
|
** so far and none of the ORDER BY terms to the right reference other
|
|
** tables in the join, then we are assured that the index can be used
|
|
** to sort because the primary key is unique and so none of the other
|
|
** columns will make any difference
|
|
*/
|
|
j = nTerm;
|
|
}
|
|
}
|
|
|
|
*pbRev = sortOrder!=0;
|
|
if( j>=nTerm ){
|
|
/* All terms of the ORDER BY clause are covered by this index so
|
|
** this index can be used for sorting. */
|
|
return 1;
|
|
}
|
|
if( pIdx->onError!=OE_None && i==pIdx->nColumn
|
|
&& !referencesOtherTables(pOrderBy, pMaskSet, j, base) ){
|
|
/* All terms of this index match some prefix of the ORDER BY clause
|
|
** and the index is UNIQUE and no terms on the tail of the ORDER BY
|
|
** clause reference other tables in a join. If this is all true then
|
|
** the order by clause is superfluous. */
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** Check table to see if the ORDER BY clause in pOrderBy can be satisfied
|
|
** by sorting in order of ROWID. Return true if so and set *pbRev to be
|
|
** true for reverse ROWID and false for forward ROWID order.
|
|
*/
|
|
static int sortableByRowid(
|
|
int base, /* Cursor number for table to be sorted */
|
|
ExprList *pOrderBy, /* The ORDER BY clause */
|
|
WhereMaskSet *pMaskSet, /* Mapping from table cursors to bitmaps */
|
|
int *pbRev /* Set to 1 if ORDER BY is DESC */
|
|
){
|
|
Expr *p;
|
|
|
|
assert( pOrderBy!=0 );
|
|
assert( pOrderBy->nExpr>0 );
|
|
p = pOrderBy->a[0].pExpr;
|
|
if( p->op==TK_COLUMN && p->iTable==base && p->iColumn==-1
|
|
&& !referencesOtherTables(pOrderBy, pMaskSet, 1, base) ){
|
|
*pbRev = pOrderBy->a[0].sortOrder;
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** Prepare a crude estimate of the logarithm of the input value.
|
|
** The results need not be exact. This is only used for estimating
|
|
** the total cost of performing operations with O(logN) or O(NlogN)
|
|
** complexity. Because N is just a guess, it is no great tragedy if
|
|
** logN is a little off.
|
|
*/
|
|
static double estLog(double N){
|
|
double logN = 1;
|
|
double x = 10;
|
|
while( N>x ){
|
|
logN += 1;
|
|
x *= 10;
|
|
}
|
|
return logN;
|
|
}
|
|
|
|
/*
|
|
** Two routines for printing the content of an sqlite3_index_info
|
|
** structure. Used for testing and debugging only. If neither
|
|
** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines
|
|
** are no-ops.
|
|
*/
|
|
#if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_DEBUG)
|
|
static void TRACE_IDX_INPUTS(sqlite3_index_info *p){
|
|
int i;
|
|
if( !sqlite3WhereTrace ) return;
|
|
for(i=0; i<p->nConstraint; i++){
|
|
sqlite3DebugPrintf(" constraint[%d]: col=%d termid=%d op=%d usabled=%d\n",
|
|
i,
|
|
p->aConstraint[i].iColumn,
|
|
p->aConstraint[i].iTermOffset,
|
|
p->aConstraint[i].op,
|
|
p->aConstraint[i].usable);
|
|
}
|
|
for(i=0; i<p->nOrderBy; i++){
|
|
sqlite3DebugPrintf(" orderby[%d]: col=%d desc=%d\n",
|
|
i,
|
|
p->aOrderBy[i].iColumn,
|
|
p->aOrderBy[i].desc);
|
|
}
|
|
}
|
|
static void TRACE_IDX_OUTPUTS(sqlite3_index_info *p){
|
|
int i;
|
|
if( !sqlite3WhereTrace ) return;
|
|
for(i=0; i<p->nConstraint; i++){
|
|
sqlite3DebugPrintf(" usage[%d]: argvIdx=%d omit=%d\n",
|
|
i,
|
|
p->aConstraintUsage[i].argvIndex,
|
|
p->aConstraintUsage[i].omit);
|
|
}
|
|
sqlite3DebugPrintf(" idxNum=%d\n", p->idxNum);
|
|
sqlite3DebugPrintf(" idxStr=%s\n", p->idxStr);
|
|
sqlite3DebugPrintf(" orderByConsumed=%d\n", p->orderByConsumed);
|
|
sqlite3DebugPrintf(" estimatedCost=%g\n", p->estimatedCost);
|
|
}
|
|
#else
|
|
#define TRACE_IDX_INPUTS(A)
|
|
#define TRACE_IDX_OUTPUTS(A)
|
|
#endif
|
|
|
|
/*
|
|
** Required because bestIndex() is called by bestOrClauseIndex()
|
|
*/
|
|
static void bestIndex(
|
|
Parse*, WhereClause*, struct SrcList_item*, Bitmask, ExprList*, WhereCost*);
|
|
|
|
/*
|
|
** This routine attempts to find an scanning strategy that can be used
|
|
** to optimize an 'OR' expression that is part of a WHERE clause.
|
|
**
|
|
** The table associated with FROM clause term pSrc may be either a
|
|
** regular B-Tree table or a virtual table.
|
|
*/
|
|
static void bestOrClauseIndex(
|
|
Parse *pParse, /* The parsing context */
|
|
WhereClause *pWC, /* The WHERE clause */
|
|
struct SrcList_item *pSrc, /* The FROM clause term to search */
|
|
Bitmask notReady, /* Mask of cursors that are not available */
|
|
ExprList *pOrderBy, /* The ORDER BY clause */
|
|
WhereCost *pCost /* Lowest cost query plan */
|
|
){
|
|
#ifndef SQLITE_OMIT_OR_OPTIMIZATION
|
|
const int iCur = pSrc->iCursor; /* The cursor of the table to be accessed */
|
|
const Bitmask maskSrc = getMask(pWC->pMaskSet, iCur); /* Bitmask for pSrc */
|
|
WhereTerm * const pWCEnd = &pWC->a[pWC->nTerm]; /* End of pWC->a[] */
|
|
WhereTerm *pTerm; /* A single term of the WHERE clause */
|
|
|
|
/* Search the WHERE clause terms for a usable WO_OR term. */
|
|
for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
|
|
if( pTerm->eOperator==WO_OR
|
|
&& ((pTerm->prereqAll & ~maskSrc) & notReady)==0
|
|
&& (pTerm->u.pOrInfo->indexable & maskSrc)!=0
|
|
){
|
|
WhereClause * const pOrWC = &pTerm->u.pOrInfo->wc;
|
|
WhereTerm * const pOrWCEnd = &pOrWC->a[pOrWC->nTerm];
|
|
WhereTerm *pOrTerm;
|
|
int flags = WHERE_MULTI_OR;
|
|
double rTotal = 0;
|
|
double nRow = 0;
|
|
|
|
for(pOrTerm=pOrWC->a; pOrTerm<pOrWCEnd; pOrTerm++){
|
|
WhereCost sTermCost;
|
|
WHERETRACE(("... Multi-index OR testing for term %d of %d....\n",
|
|
(pOrTerm - pOrWC->a), (pTerm - pWC->a)
|
|
));
|
|
if( pOrTerm->eOperator==WO_AND ){
|
|
WhereClause *pAndWC = &pOrTerm->u.pAndInfo->wc;
|
|
bestIndex(pParse, pAndWC, pSrc, notReady, 0, &sTermCost);
|
|
}else if( pOrTerm->leftCursor==iCur ){
|
|
WhereClause tempWC;
|
|
tempWC.pParse = pWC->pParse;
|
|
tempWC.pMaskSet = pWC->pMaskSet;
|
|
tempWC.op = TK_AND;
|
|
tempWC.a = pOrTerm;
|
|
tempWC.nTerm = 1;
|
|
bestIndex(pParse, &tempWC, pSrc, notReady, 0, &sTermCost);
|
|
}else{
|
|
continue;
|
|
}
|
|
rTotal += sTermCost.rCost;
|
|
nRow += sTermCost.nRow;
|
|
if( rTotal>=pCost->rCost ) break;
|
|
}
|
|
|
|
/* If there is an ORDER BY clause, increase the scan cost to account
|
|
** for the cost of the sort. */
|
|
if( pOrderBy!=0 ){
|
|
rTotal += nRow*estLog(nRow);
|
|
WHERETRACE(("... sorting increases OR cost to %.9g\n", rTotal));
|
|
}
|
|
|
|
/* If the cost of scanning using this OR term for optimization is
|
|
** less than the current cost stored in pCost, replace the contents
|
|
** of pCost. */
|
|
WHERETRACE(("... multi-index OR cost=%.9g nrow=%.9g\n", rTotal, nRow));
|
|
if( rTotal<pCost->rCost ){
|
|
pCost->rCost = rTotal;
|
|
pCost->nRow = nRow;
|
|
pCost->plan.wsFlags = flags;
|
|
pCost->plan.u.pTerm = pTerm;
|
|
}
|
|
}
|
|
}
|
|
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
|
|
}
|
|
|
|
#ifndef SQLITE_OMIT_VIRTUALTABLE
|
|
/*
|
|
** Allocate and populate an sqlite3_index_info structure. It is the
|
|
** responsibility of the caller to eventually release the structure
|
|
** by passing the pointer returned by this function to sqlite3_free().
|
|
*/
|
|
static sqlite3_index_info *allocateIndexInfo(
|
|
Parse *pParse,
|
|
WhereClause *pWC,
|
|
struct SrcList_item *pSrc,
|
|
ExprList *pOrderBy
|
|
){
|
|
int i, j;
|
|
int nTerm;
|
|
struct sqlite3_index_constraint *pIdxCons;
|
|
struct sqlite3_index_orderby *pIdxOrderBy;
|
|
struct sqlite3_index_constraint_usage *pUsage;
|
|
WhereTerm *pTerm;
|
|
int nOrderBy;
|
|
sqlite3_index_info *pIdxInfo;
|
|
|
|
WHERETRACE(("Recomputing index info for %s...\n", pSrc->pTab->zName));
|
|
|
|
/* Count the number of possible WHERE clause constraints referring
|
|
** to this virtual table */
|
|
for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
|
|
if( pTerm->leftCursor != pSrc->iCursor ) continue;
|
|
assert( (pTerm->eOperator&(pTerm->eOperator-1))==0 );
|
|
testcase( pTerm->eOperator==WO_IN );
|
|
testcase( pTerm->eOperator==WO_ISNULL );
|
|
if( pTerm->eOperator & (WO_IN|WO_ISNULL) ) continue;
|
|
nTerm++;
|
|
}
|
|
|
|
/* If the ORDER BY clause contains only columns in the current
|
|
** virtual table then allocate space for the aOrderBy part of
|
|
** the sqlite3_index_info structure.
|
|
*/
|
|
nOrderBy = 0;
|
|
if( pOrderBy ){
|
|
for(i=0; i<pOrderBy->nExpr; i++){
|
|
Expr *pExpr = pOrderBy->a[i].pExpr;
|
|
if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break;
|
|
}
|
|
if( i==pOrderBy->nExpr ){
|
|
nOrderBy = pOrderBy->nExpr;
|
|
}
|
|
}
|
|
|
|
/* Allocate the sqlite3_index_info structure
|
|
*/
|
|
pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo)
|
|
+ (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm
|
|
+ sizeof(*pIdxOrderBy)*nOrderBy );
|
|
if( pIdxInfo==0 ){
|
|
sqlite3ErrorMsg(pParse, "out of memory");
|
|
/* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
|
|
return 0;
|
|
}
|
|
|
|
/* Initialize the structure. The sqlite3_index_info structure contains
|
|
** many fields that are declared "const" to prevent xBestIndex from
|
|
** changing them. We have to do some funky casting in order to
|
|
** initialize those fields.
|
|
*/
|
|
pIdxCons = (struct sqlite3_index_constraint*)&pIdxInfo[1];
|
|
pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm];
|
|
pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy];
|
|
*(int*)&pIdxInfo->nConstraint = nTerm;
|
|
*(int*)&pIdxInfo->nOrderBy = nOrderBy;
|
|
*(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint = pIdxCons;
|
|
*(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy;
|
|
*(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage =
|
|
pUsage;
|
|
|
|
for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
|
|
if( pTerm->leftCursor != pSrc->iCursor ) continue;
|
|
assert( (pTerm->eOperator&(pTerm->eOperator-1))==0 );
|
|
testcase( pTerm->eOperator==WO_IN );
|
|
testcase( pTerm->eOperator==WO_ISNULL );
|
|
if( pTerm->eOperator & (WO_IN|WO_ISNULL) ) continue;
|
|
pIdxCons[j].iColumn = pTerm->u.leftColumn;
|
|
pIdxCons[j].iTermOffset = i;
|
|
pIdxCons[j].op = (u8)pTerm->eOperator;
|
|
/* The direct assignment in the previous line is possible only because
|
|
** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical. The
|
|
** following asserts verify this fact. */
|
|
assert( WO_EQ==SQLITE_INDEX_CONSTRAINT_EQ );
|
|
assert( WO_LT==SQLITE_INDEX_CONSTRAINT_LT );
|
|
assert( WO_LE==SQLITE_INDEX_CONSTRAINT_LE );
|
|
assert( WO_GT==SQLITE_INDEX_CONSTRAINT_GT );
|
|
assert( WO_GE==SQLITE_INDEX_CONSTRAINT_GE );
|
|
assert( WO_MATCH==SQLITE_INDEX_CONSTRAINT_MATCH );
|
|
assert( pTerm->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_MATCH) );
|
|
j++;
|
|
}
|
|
for(i=0; i<nOrderBy; i++){
|
|
Expr *pExpr = pOrderBy->a[i].pExpr;
|
|
pIdxOrderBy[i].iColumn = pExpr->iColumn;
|
|
pIdxOrderBy[i].desc = pOrderBy->a[i].sortOrder;
|
|
}
|
|
|
|
return pIdxInfo;
|
|
}
|
|
|
|
/*
|
|
** The table object reference passed as the second argument to this function
|
|
** must represent a virtual table. This function invokes the xBestIndex()
|
|
** method of the virtual table with the sqlite3_index_info pointer passed
|
|
** as the argument.
|
|
**
|
|
** If an error occurs, pParse is populated with an error message and a
|
|
** non-zero value is returned. Otherwise, 0 is returned and the output
|
|
** part of the sqlite3_index_info structure is left populated.
|
|
**
|
|
** Whether or not an error is returned, it is the responsibility of the
|
|
** caller to eventually free p->idxStr if p->needToFreeIdxStr indicates
|
|
** that this is required.
|
|
*/
|
|
static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){
|
|
sqlite3_vtab *pVtab = pTab->pVtab;
|
|
int i;
|
|
int rc;
|
|
|
|
(void)sqlite3SafetyOff(pParse->db);
|
|
WHERETRACE(("xBestIndex for %s\n", pTab->zName));
|
|
TRACE_IDX_INPUTS(p);
|
|
rc = pVtab->pModule->xBestIndex(pVtab, p);
|
|
TRACE_IDX_OUTPUTS(p);
|
|
(void)sqlite3SafetyOn(pParse->db);
|
|
|
|
if( rc!=SQLITE_OK ){
|
|
if( rc==SQLITE_NOMEM ){
|
|
pParse->db->mallocFailed = 1;
|
|
}else if( !pVtab->zErrMsg ){
|
|
sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc));
|
|
}else{
|
|
sqlite3ErrorMsg(pParse, "%s", pVtab->zErrMsg);
|
|
}
|
|
}
|
|
sqlite3DbFree(pParse->db, pVtab->zErrMsg);
|
|
pVtab->zErrMsg = 0;
|
|
|
|
for(i=0; i<p->nConstraint; i++){
|
|
if( !p->aConstraint[i].usable && p->aConstraintUsage[i].argvIndex>0 ){
|
|
sqlite3ErrorMsg(pParse,
|
|
"table %s: xBestIndex returned an invalid plan", pTab->zName);
|
|
}
|
|
}
|
|
|
|
return pParse->nErr;
|
|
}
|
|
|
|
|
|
/*
|
|
** Compute the best index for a virtual table.
|
|
**
|
|
** The best index is computed by the xBestIndex method of the virtual
|
|
** table module. This routine is really just a wrapper that sets up
|
|
** the sqlite3_index_info structure that is used to communicate with
|
|
** xBestIndex.
|
|
**
|
|
** In a join, this routine might be called multiple times for the
|
|
** same virtual table. The sqlite3_index_info structure is created
|
|
** and initialized on the first invocation and reused on all subsequent
|
|
** invocations. The sqlite3_index_info structure is also used when
|
|
** code is generated to access the virtual table. The whereInfoDelete()
|
|
** routine takes care of freeing the sqlite3_index_info structure after
|
|
** everybody has finished with it.
|
|
*/
|
|
static void bestVirtualIndex(
|
|
Parse *pParse, /* The parsing context */
|
|
WhereClause *pWC, /* The WHERE clause */
|
|
struct SrcList_item *pSrc, /* The FROM clause term to search */
|
|
Bitmask notReady, /* Mask of cursors that are not available */
|
|
ExprList *pOrderBy, /* The order by clause */
|
|
WhereCost *pCost, /* Lowest cost query plan */
|
|
sqlite3_index_info **ppIdxInfo /* Index information passed to xBestIndex */
|
|
){
|
|
Table *pTab = pSrc->pTab;
|
|
sqlite3_index_info *pIdxInfo;
|
|
struct sqlite3_index_constraint *pIdxCons;
|
|
struct sqlite3_index_constraint_usage *pUsage;
|
|
WhereTerm *pTerm;
|
|
int i, j;
|
|
int nOrderBy;
|
|
|
|
/* Make sure wsFlags is initialized to some sane value. Otherwise, if the
|
|
** malloc in allocateIndexInfo() fails and this function returns leaving
|
|
** wsFlags in an uninitialized state, the caller may behave unpredictably.
|
|
*/
|
|
memset(pCost, 0, sizeof(*pCost));
|
|
pCost->plan.wsFlags = WHERE_VIRTUALTABLE;
|
|
|
|
/* If the sqlite3_index_info structure has not been previously
|
|
** allocated and initialized, then allocate and initialize it now.
|
|
*/
|
|
pIdxInfo = *ppIdxInfo;
|
|
if( pIdxInfo==0 ){
|
|
*ppIdxInfo = pIdxInfo = allocateIndexInfo(pParse, pWC, pSrc, pOrderBy);
|
|
}
|
|
if( pIdxInfo==0 ){
|
|
return;
|
|
}
|
|
|
|
/* At this point, the sqlite3_index_info structure that pIdxInfo points
|
|
** to will have been initialized, either during the current invocation or
|
|
** during some prior invocation. Now we just have to customize the
|
|
** details of pIdxInfo for the current invocation and pass it to
|
|
** xBestIndex.
|
|
*/
|
|
|
|
/* The module name must be defined. Also, by this point there must
|
|
** be a pointer to an sqlite3_vtab structure. Otherwise
|
|
** sqlite3ViewGetColumnNames() would have picked up the error.
|
|
*/
|
|
assert( pTab->azModuleArg && pTab->azModuleArg[0] );
|
|
assert( pTab->pVtab );
|
|
|
|
/* Set the aConstraint[].usable fields and initialize all
|
|
** output variables to zero.
|
|
**
|
|
** aConstraint[].usable is true for constraints where the right-hand
|
|
** side contains only references to tables to the left of the current
|
|
** table. In other words, if the constraint is of the form:
|
|
**
|
|
** column = expr
|
|
**
|
|
** and we are evaluating a join, then the constraint on column is
|
|
** only valid if all tables referenced in expr occur to the left
|
|
** of the table containing column.
|
|
**
|
|
** The aConstraints[] array contains entries for all constraints
|
|
** on the current table. That way we only have to compute it once
|
|
** even though we might try to pick the best index multiple times.
|
|
** For each attempt at picking an index, the order of tables in the
|
|
** join might be different so we have to recompute the usable flag
|
|
** each time.
|
|
*/
|
|
pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
|
|
pUsage = pIdxInfo->aConstraintUsage;
|
|
for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){
|
|
j = pIdxCons->iTermOffset;
|
|
pTerm = &pWC->a[j];
|
|
pIdxCons->usable = (pTerm->prereqRight & notReady)==0 ?1:0;
|
|
}
|
|
memset(pUsage, 0, sizeof(pUsage[0])*pIdxInfo->nConstraint);
|
|
if( pIdxInfo->needToFreeIdxStr ){
|
|
sqlite3_free(pIdxInfo->idxStr);
|
|
}
|
|
pIdxInfo->idxStr = 0;
|
|
pIdxInfo->idxNum = 0;
|
|
pIdxInfo->needToFreeIdxStr = 0;
|
|
pIdxInfo->orderByConsumed = 0;
|
|
/* ((double)2) In case of SQLITE_OMIT_FLOATING_POINT... */
|
|
pIdxInfo->estimatedCost = SQLITE_BIG_DBL / ((double)2);
|
|
nOrderBy = pIdxInfo->nOrderBy;
|
|
if( !pOrderBy ){
|
|
pIdxInfo->nOrderBy = 0;
|
|
}
|
|
|
|
if( vtabBestIndex(pParse, pTab, pIdxInfo) ){
|
|
return;
|
|
}
|
|
|
|
/* The cost is not allowed to be larger than SQLITE_BIG_DBL (the
|
|
** inital value of lowestCost in this loop. If it is, then the
|
|
** (cost<lowestCost) test below will never be true.
|
|
**
|
|
** Use "(double)2" instead of "2.0" in case OMIT_FLOATING_POINT
|
|
** is defined.
|
|
*/
|
|
if( (SQLITE_BIG_DBL/((double)2))<pIdxInfo->estimatedCost ){
|
|
pCost->rCost = (SQLITE_BIG_DBL/((double)2));
|
|
}else{
|
|
pCost->rCost = pIdxInfo->estimatedCost;
|
|
}
|
|
pCost->plan.u.pVtabIdx = pIdxInfo;
|
|
if( pIdxInfo && pIdxInfo->orderByConsumed ){
|
|
pCost->plan.wsFlags |= WHERE_ORDERBY;
|
|
}
|
|
pCost->plan.nEq = 0;
|
|
pIdxInfo->nOrderBy = nOrderBy;
|
|
|
|
/* Try to find a more efficient access pattern by using multiple indexes
|
|
** to optimize an OR expression within the WHERE clause.
|
|
*/
|
|
bestOrClauseIndex(pParse, pWC, pSrc, notReady, pOrderBy, pCost);
|
|
}
|
|
#endif /* SQLITE_OMIT_VIRTUALTABLE */
|
|
|
|
/*
|
|
** Find the query plan for accessing a particular table. Write the
|
|
** best query plan and its cost into the WhereCost object supplied as the
|
|
** last parameter.
|
|
**
|
|
** The lowest cost plan wins. The cost is an estimate of the amount of
|
|
** CPU and disk I/O need to process the request using the selected plan.
|
|
** Factors that influence cost include:
|
|
**
|
|
** * The estimated number of rows that will be retrieved. (The
|
|
** fewer the better.)
|
|
**
|
|
** * Whether or not sorting must occur.
|
|
**
|
|
** * Whether or not there must be separate lookups in the
|
|
** index and in the main table.
|
|
**
|
|
** If there was an INDEXED BY clause (pSrc->pIndex) attached to the table in
|
|
** the SQL statement, then this function only considers plans using the
|
|
** named index. If no such plan is found, then the returned cost is
|
|
** SQLITE_BIG_DBL. If a plan is found that uses the named index,
|
|
** then the cost is calculated in the usual way.
|
|
**
|
|
** If a NOT INDEXED clause (pSrc->notIndexed!=0) was attached to the table
|
|
** in the SELECT statement, then no indexes are considered. However, the
|
|
** selected plan may still take advantage of the tables built-in rowid
|
|
** index.
|
|
*/
|
|
static void bestBtreeIndex(
|
|
Parse *pParse, /* The parsing context */
|
|
WhereClause *pWC, /* The WHERE clause */
|
|
struct SrcList_item *pSrc, /* The FROM clause term to search */
|
|
Bitmask notReady, /* Mask of cursors that are not available */
|
|
ExprList *pOrderBy, /* The ORDER BY clause */
|
|
WhereCost *pCost /* Lowest cost query plan */
|
|
){
|
|
WhereTerm *pTerm; /* A single term of the WHERE clause */
|
|
int iCur = pSrc->iCursor; /* The cursor of the table to be accessed */
|
|
Index *pProbe; /* An index we are evaluating */
|
|
int rev; /* True to scan in reverse order */
|
|
int wsFlags; /* Flags associated with pProbe */
|
|
int nEq; /* Number of == or IN constraints */
|
|
int eqTermMask; /* Mask of valid equality operators */
|
|
double cost; /* Cost of using pProbe */
|
|
double nRow; /* Estimated number of rows in result set */
|
|
int i; /* Loop counter */
|
|
|
|
WHERETRACE(("bestIndex: tbl=%s notReady=%llx\n", pSrc->pTab->zName,notReady));
|
|
pProbe = pSrc->pTab->pIndex;
|
|
if( pSrc->notIndexed ){
|
|
pProbe = 0;
|
|
}
|
|
|
|
/* If the table has no indices and there are no terms in the where
|
|
** clause that refer to the ROWID, then we will never be able to do
|
|
** anything other than a full table scan on this table. We might as
|
|
** well put it first in the join order. That way, perhaps it can be
|
|
** referenced by other tables in the join.
|
|
*/
|
|
memset(pCost, 0, sizeof(*pCost));
|
|
if( pProbe==0 &&
|
|
findTerm(pWC, iCur, -1, 0, WO_EQ|WO_IN|WO_LT|WO_LE|WO_GT|WO_GE,0)==0 &&
|
|
(pOrderBy==0 || !sortableByRowid(iCur, pOrderBy, pWC->pMaskSet, &rev)) ){
|
|
if( pParse->db->flags & SQLITE_ReverseOrder ){
|
|
/* For application testing, randomly reverse the output order for
|
|
** SELECT statements that omit the ORDER BY clause. This will help
|
|
** to find cases where
|
|
*/
|
|
pCost->plan.wsFlags |= WHERE_REVERSE;
|
|
}
|
|
return;
|
|
}
|
|
pCost->rCost = SQLITE_BIG_DBL;
|
|
|
|
/* Check for a rowid=EXPR or rowid IN (...) constraints. If there was
|
|
** an INDEXED BY clause attached to this table, skip this step.
|
|
*/
|
|
if( !pSrc->pIndex ){
|
|
pTerm = findTerm(pWC, iCur, -1, notReady, WO_EQ|WO_IN, 0);
|
|
if( pTerm ){
|
|
Expr *pExpr;
|
|
pCost->plan.wsFlags = WHERE_ROWID_EQ;
|
|
if( pTerm->eOperator & WO_EQ ){
|
|
/* Rowid== is always the best pick. Look no further. Because only
|
|
** a single row is generated, output is always in sorted order */
|
|
pCost->plan.wsFlags = WHERE_ROWID_EQ | WHERE_UNIQUE;
|
|
pCost->plan.nEq = 1;
|
|
WHERETRACE(("... best is rowid\n"));
|
|
pCost->rCost = 0;
|
|
pCost->nRow = 1;
|
|
return;
|
|
}else if( !ExprHasProperty((pExpr = pTerm->pExpr), EP_xIsSelect)
|
|
&& pExpr->x.pList
|
|
){
|
|
/* Rowid IN (LIST): cost is NlogN where N is the number of list
|
|
** elements. */
|
|
pCost->rCost = pCost->nRow = pExpr->x.pList->nExpr;
|
|
pCost->rCost *= estLog(pCost->rCost);
|
|
}else{
|
|
/* Rowid IN (SELECT): cost is NlogN where N is the number of rows
|
|
** in the result of the inner select. We have no way to estimate
|
|
** that value so make a wild guess. */
|
|
pCost->nRow = 100;
|
|
pCost->rCost = 200;
|
|
}
|
|
WHERETRACE(("... rowid IN cost: %.9g\n", pCost->rCost));
|
|
}
|
|
|
|
/* Estimate the cost of a table scan. If we do not know how many
|
|
** entries are in the table, use 1 million as a guess.
|
|
*/
|
|
cost = pProbe ? pProbe->aiRowEst[0] : 1000000;
|
|
WHERETRACE(("... table scan base cost: %.9g\n", cost));
|
|
wsFlags = WHERE_ROWID_RANGE;
|
|
|
|
/* Check for constraints on a range of rowids in a table scan.
|
|
*/
|
|
pTerm = findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE|WO_GT|WO_GE, 0);
|
|
if( pTerm ){
|
|
if( findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE, 0) ){
|
|
wsFlags |= WHERE_TOP_LIMIT;
|
|
cost /= 3; /* Guess that rowid<EXPR eliminates two-thirds of rows */
|
|
}
|
|
if( findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0) ){
|
|
wsFlags |= WHERE_BTM_LIMIT;
|
|
cost /= 3; /* Guess that rowid>EXPR eliminates two-thirds of rows */
|
|
}
|
|
WHERETRACE(("... rowid range reduces cost to %.9g\n", cost));
|
|
}else{
|
|
wsFlags = 0;
|
|
}
|
|
nRow = cost;
|
|
|
|
/* If the table scan does not satisfy the ORDER BY clause, increase
|
|
** the cost by NlogN to cover the expense of sorting. */
|
|
if( pOrderBy ){
|
|
if( sortableByRowid(iCur, pOrderBy, pWC->pMaskSet, &rev) ){
|
|
wsFlags |= WHERE_ORDERBY|WHERE_ROWID_RANGE;
|
|
if( rev ){
|
|
wsFlags |= WHERE_REVERSE;
|
|
}
|
|
}else{
|
|
cost += cost*estLog(cost);
|
|
WHERETRACE(("... sorting increases cost to %.9g\n", cost));
|
|
}
|
|
}else if( pParse->db->flags & SQLITE_ReverseOrder ){
|
|
/* For application testing, randomly reverse the output order for
|
|
** SELECT statements that omit the ORDER BY clause. This will help
|
|
** to find cases where
|
|
*/
|
|
wsFlags |= WHERE_REVERSE;
|
|
}
|
|
|
|
/* Remember this case if it is the best so far */
|
|
if( cost<pCost->rCost ){
|
|
pCost->rCost = cost;
|
|
pCost->nRow = nRow;
|
|
pCost->plan.wsFlags = wsFlags;
|
|
}
|
|
}
|
|
|
|
bestOrClauseIndex(pParse, pWC, pSrc, notReady, pOrderBy, pCost);
|
|
|
|
/* If the pSrc table is the right table of a LEFT JOIN then we may not
|
|
** use an index to satisfy IS NULL constraints on that table. This is
|
|
** because columns might end up being NULL if the table does not match -
|
|
** a circumstance which the index cannot help us discover. Ticket #2177.
|
|
*/
|
|
if( (pSrc->jointype & JT_LEFT)!=0 ){
|
|
eqTermMask = WO_EQ|WO_IN;
|
|
}else{
|
|
eqTermMask = WO_EQ|WO_IN|WO_ISNULL;
|
|
}
|
|
|
|
/* Look at each index.
|
|
*/
|
|
if( pSrc->pIndex ){
|
|
pProbe = pSrc->pIndex;
|
|
}
|
|
for(; pProbe; pProbe=(pSrc->pIndex ? 0 : pProbe->pNext)){
|
|
double inMultiplier = 1; /* Number of equality look-ups needed */
|
|
int inMultIsEst = 0; /* True if inMultiplier is an estimate */
|
|
|
|
WHERETRACE(("... index %s:\n", pProbe->zName));
|
|
|
|
/* Count the number of columns in the index that are satisfied
|
|
** by x=EXPR or x IS NULL constraints or x IN (...) constraints.
|
|
** For a term of the form x=EXPR or x IS NULL we only have to do
|
|
** a single binary search. But for x IN (...) we have to do a
|
|
** number of binary searched
|
|
** equal to the number of entries on the RHS of the IN operator.
|
|
** The inMultipler variable with try to estimate the number of
|
|
** binary searches needed.
|
|
*/
|
|
wsFlags = 0;
|
|
for(i=0; i<pProbe->nColumn; i++){
|
|
int j = pProbe->aiColumn[i];
|
|
pTerm = findTerm(pWC, iCur, j, notReady, eqTermMask, pProbe);
|
|
if( pTerm==0 ) break;
|
|
wsFlags |= WHERE_COLUMN_EQ;
|
|
if( pTerm->eOperator & WO_IN ){
|
|
Expr *pExpr = pTerm->pExpr;
|
|
wsFlags |= WHERE_COLUMN_IN;
|
|
if( ExprHasProperty(pExpr, EP_xIsSelect) ){
|
|
inMultiplier *= 25;
|
|
inMultIsEst = 1;
|
|
}else if( pExpr->x.pList ){
|
|
inMultiplier *= pExpr->x.pList->nExpr + 1;
|
|
}
|
|
}else if( pTerm->eOperator & WO_ISNULL ){
|
|
wsFlags |= WHERE_COLUMN_NULL;
|
|
}
|
|
}
|
|
nRow = pProbe->aiRowEst[i] * inMultiplier;
|
|
/* If inMultiplier is an estimate and that estimate results in an
|
|
** nRow it that is more than half number of rows in the table,
|
|
** then reduce inMultipler */
|
|
if( inMultIsEst && nRow*2 > pProbe->aiRowEst[0] ){
|
|
nRow = pProbe->aiRowEst[0]/2;
|
|
inMultiplier = nRow/pProbe->aiRowEst[i];
|
|
}
|
|
cost = nRow + inMultiplier*estLog(pProbe->aiRowEst[0]);
|
|
nEq = i;
|
|
if( pProbe->onError!=OE_None && nEq==pProbe->nColumn ){
|
|
testcase( wsFlags & WHERE_COLUMN_IN );
|
|
testcase( wsFlags & WHERE_COLUMN_NULL );
|
|
if( (wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0 ){
|
|
wsFlags |= WHERE_UNIQUE;
|
|
}
|
|
}
|
|
WHERETRACE(("...... nEq=%d inMult=%.9g nRow=%.9g cost=%.9g\n",
|
|
nEq, inMultiplier, nRow, cost));
|
|
|
|
/* Look for range constraints. Assume that each range constraint
|
|
** makes the search space 1/3rd smaller.
|
|
*/
|
|
if( nEq<pProbe->nColumn ){
|
|
int j = pProbe->aiColumn[nEq];
|
|
pTerm = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pProbe);
|
|
if( pTerm ){
|
|
wsFlags |= WHERE_COLUMN_RANGE;
|
|
if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pProbe) ){
|
|
wsFlags |= WHERE_TOP_LIMIT;
|
|
cost /= 3;
|
|
nRow /= 3;
|
|
}
|
|
if( findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pProbe) ){
|
|
wsFlags |= WHERE_BTM_LIMIT;
|
|
cost /= 3;
|
|
nRow /= 3;
|
|
}
|
|
WHERETRACE(("...... range reduces nRow to %.9g and cost to %.9g\n",
|
|
nRow, cost));
|
|
}
|
|
}
|
|
|
|
/* Add the additional cost of sorting if that is a factor.
|
|
*/
|
|
if( pOrderBy ){
|
|
if( (wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0
|
|
&& isSortingIndex(pParse,pWC->pMaskSet,pProbe,iCur,pOrderBy,nEq,&rev)
|
|
){
|
|
if( wsFlags==0 ){
|
|
wsFlags = WHERE_COLUMN_RANGE;
|
|
}
|
|
wsFlags |= WHERE_ORDERBY;
|
|
if( rev ){
|
|
wsFlags |= WHERE_REVERSE;
|
|
}
|
|
}else{
|
|
cost += cost*estLog(cost);
|
|
WHERETRACE(("...... orderby increases cost to %.9g\n", cost));
|
|
}
|
|
}else if( pParse->db->flags & SQLITE_ReverseOrder ){
|
|
/* For application testing, randomly reverse the output order for
|
|
** SELECT statements that omit the ORDER BY clause. This will help
|
|
** to find cases where
|
|
*/
|
|
wsFlags |= WHERE_REVERSE;
|
|
}
|
|
|
|
/* Check to see if we can get away with using just the index without
|
|
** ever reading the table. If that is the case, then halve the
|
|
** cost of this index.
|
|
*/
|
|
if( wsFlags && pSrc->colUsed < (((Bitmask)1)<<(BMS-1)) ){
|
|
Bitmask m = pSrc->colUsed;
|
|
int j;
|
|
for(j=0; j<pProbe->nColumn; j++){
|
|
int x = pProbe->aiColumn[j];
|
|
if( x<BMS-1 ){
|
|
m &= ~(((Bitmask)1)<<x);
|
|
}
|
|
}
|
|
if( m==0 ){
|
|
wsFlags |= WHERE_IDX_ONLY;
|
|
cost /= 2;
|
|
WHERETRACE(("...... idx-only reduces cost to %.9g\n", cost));
|
|
}
|
|
}
|
|
|
|
/* If this index has achieved the lowest cost so far, then use it.
|
|
*/
|
|
if( wsFlags!=0 && cost < pCost->rCost ){
|
|
pCost->rCost = cost;
|
|
pCost->nRow = nRow;
|
|
pCost->plan.wsFlags = wsFlags;
|
|
pCost->plan.nEq = nEq;
|
|
assert( pCost->plan.wsFlags & WHERE_INDEXED );
|
|
pCost->plan.u.pIdx = pProbe;
|
|
}
|
|
}
|
|
|
|
/* Report the best result
|
|
*/
|
|
pCost->plan.wsFlags |= eqTermMask;
|
|
WHERETRACE(("best index is %s, cost=%.9g, nrow=%.9g, wsFlags=%x, nEq=%d\n",
|
|
(pCost->plan.wsFlags & WHERE_INDEXED)!=0 ?
|
|
pCost->plan.u.pIdx->zName : "(none)", pCost->nRow,
|
|
pCost->rCost, pCost->plan.wsFlags, pCost->plan.nEq));
|
|
}
|
|
|
|
/*
|
|
** Find the query plan for accessing table pSrc->pTab. Write the
|
|
** best query plan and its cost into the WhereCost object supplied
|
|
** as the last parameter. This function may calculate the cost of
|
|
** both real and virtual table scans.
|
|
*/
|
|
static void bestIndex(
|
|
Parse *pParse, /* The parsing context */
|
|
WhereClause *pWC, /* The WHERE clause */
|
|
struct SrcList_item *pSrc, /* The FROM clause term to search */
|
|
Bitmask notReady, /* Mask of cursors that are not available */
|
|
ExprList *pOrderBy, /* The ORDER BY clause */
|
|
WhereCost *pCost /* Lowest cost query plan */
|
|
){
|
|
if( IsVirtual(pSrc->pTab) ){
|
|
sqlite3_index_info *p = 0;
|
|
bestVirtualIndex(pParse, pWC, pSrc, notReady, pOrderBy, pCost, &p);
|
|
if( p->needToFreeIdxStr ){
|
|
sqlite3_free(p->idxStr);
|
|
}
|
|
sqlite3DbFree(pParse->db, p);
|
|
}else{
|
|
bestBtreeIndex(pParse, pWC, pSrc, notReady, pOrderBy, pCost);
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Disable a term in the WHERE clause. Except, do not disable the term
|
|
** if it controls a LEFT OUTER JOIN and it did not originate in the ON
|
|
** or USING clause of that join.
|
|
**
|
|
** Consider the term t2.z='ok' in the following queries:
|
|
**
|
|
** (1) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok'
|
|
** (2) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok'
|
|
** (3) SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok'
|
|
**
|
|
** The t2.z='ok' is disabled in the in (2) because it originates
|
|
** in the ON clause. The term is disabled in (3) because it is not part
|
|
** of a LEFT OUTER JOIN. In (1), the term is not disabled.
|
|
**
|
|
** Disabling a term causes that term to not be tested in the inner loop
|
|
** of the join. Disabling is an optimization. When terms are satisfied
|
|
** by indices, we disable them to prevent redundant tests in the inner
|
|
** loop. We would get the correct results if nothing were ever disabled,
|
|
** but joins might run a little slower. The trick is to disable as much
|
|
** as we can without disabling too much. If we disabled in (1), we'd get
|
|
** the wrong answer. See ticket #813.
|
|
*/
|
|
static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
|
|
if( pTerm
|
|
&& ALWAYS((pTerm->wtFlags & TERM_CODED)==0)
|
|
&& (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
|
|
){
|
|
pTerm->wtFlags |= TERM_CODED;
|
|
if( pTerm->iParent>=0 ){
|
|
WhereTerm *pOther = &pTerm->pWC->a[pTerm->iParent];
|
|
if( (--pOther->nChild)==0 ){
|
|
disableTerm(pLevel, pOther);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Apply the affinities associated with the first n columns of index
|
|
** pIdx to the values in the n registers starting at base.
|
|
*/
|
|
static void codeApplyAffinity(Parse *pParse, int base, int n, Index *pIdx){
|
|
if( n>0 ){
|
|
Vdbe *v = pParse->pVdbe;
|
|
assert( v!=0 );
|
|
sqlite3VdbeAddOp2(v, OP_Affinity, base, n);
|
|
sqlite3IndexAffinityStr(v, pIdx);
|
|
sqlite3ExprCacheAffinityChange(pParse, base, n);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** Generate code for a single equality term of the WHERE clause. An equality
|
|
** term can be either X=expr or X IN (...). pTerm is the term to be
|
|
** coded.
|
|
**
|
|
** The current value for the constraint is left in register iReg.
|
|
**
|
|
** For a constraint of the form X=expr, the expression is evaluated and its
|
|
** result is left on the stack. For constraints of the form X IN (...)
|
|
** this routine sets up a loop that will iterate over all values of X.
|
|
*/
|
|
static int codeEqualityTerm(
|
|
Parse *pParse, /* The parsing context */
|
|
WhereTerm *pTerm, /* The term of the WHERE clause to be coded */
|
|
WhereLevel *pLevel, /* When level of the FROM clause we are working on */
|
|
int iTarget /* Attempt to leave results in this register */
|
|
){
|
|
Expr *pX = pTerm->pExpr;
|
|
Vdbe *v = pParse->pVdbe;
|
|
int iReg; /* Register holding results */
|
|
|
|
assert( iTarget>0 );
|
|
if( pX->op==TK_EQ ){
|
|
iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);
|
|
}else if( pX->op==TK_ISNULL ){
|
|
iReg = iTarget;
|
|
sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
|
|
#ifndef SQLITE_OMIT_SUBQUERY
|
|
}else{
|
|
int eType;
|
|
int iTab;
|
|
struct InLoop *pIn;
|
|
|
|
assert( pX->op==TK_IN );
|
|
iReg = iTarget;
|
|
eType = sqlite3FindInIndex(pParse, pX, 0);
|
|
iTab = pX->iTable;
|
|
sqlite3VdbeAddOp2(v, OP_Rewind, iTab, 0);
|
|
assert( pLevel->plan.wsFlags & WHERE_IN_ABLE );
|
|
if( pLevel->u.in.nIn==0 ){
|
|
pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
|
|
}
|
|
pLevel->u.in.nIn++;
|
|
pLevel->u.in.aInLoop =
|
|
sqlite3DbReallocOrFree(pParse->db, pLevel->u.in.aInLoop,
|
|
sizeof(pLevel->u.in.aInLoop[0])*pLevel->u.in.nIn);
|
|
pIn = pLevel->u.in.aInLoop;
|
|
if( pIn ){
|
|
pIn += pLevel->u.in.nIn - 1;
|
|
pIn->iCur = iTab;
|
|
if( eType==IN_INDEX_ROWID ){
|
|
pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iReg);
|
|
}else{
|
|
pIn->addrInTop = sqlite3VdbeAddOp3(v, OP_Column, iTab, 0, iReg);
|
|
}
|
|
sqlite3VdbeAddOp1(v, OP_IsNull, iReg);
|
|
}else{
|
|
pLevel->u.in.nIn = 0;
|
|
}
|
|
#endif
|
|
}
|
|
disableTerm(pLevel, pTerm);
|
|
return iReg;
|
|
}
|
|
|
|
/*
|
|
** Generate code that will evaluate all == and IN constraints for an
|
|
** index. The values for all constraints are left on the stack.
|
|
**
|
|
** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c).
|
|
** Suppose the WHERE clause is this: a==5 AND b IN (1,2,3) AND c>5 AND c<10
|
|
** The index has as many as three equality constraints, but in this
|
|
** example, the third "c" value is an inequality. So only two
|
|
** constraints are coded. This routine will generate code to evaluate
|
|
** a==5 and b IN (1,2,3). The current values for a and b will be stored
|
|
** in consecutive registers and the index of the first register is returned.
|
|
**
|
|
** In the example above nEq==2. But this subroutine works for any value
|
|
** of nEq including 0. If nEq==0, this routine is nearly a no-op.
|
|
** The only thing it does is allocate the pLevel->iMem memory cell.
|
|
**
|
|
** This routine always allocates at least one memory cell and returns
|
|
** the index of that memory cell. The code that
|
|
** calls this routine will use that memory cell to store the termination
|
|
** key value of the loop. If one or more IN operators appear, then
|
|
** this routine allocates an additional nEq memory cells for internal
|
|
** use.
|
|
*/
|
|
static int codeAllEqualityTerms(
|
|
Parse *pParse, /* Parsing context */
|
|
WhereLevel *pLevel, /* Which nested loop of the FROM we are coding */
|
|
WhereClause *pWC, /* The WHERE clause */
|
|
Bitmask notReady, /* Which parts of FROM have not yet been coded */
|
|
int nExtraReg /* Number of extra registers to allocate */
|
|
){
|
|
int nEq = pLevel->plan.nEq; /* The number of == or IN constraints to code */
|
|
Vdbe *v = pParse->pVdbe; /* The vm under construction */
|
|
Index *pIdx; /* The index being used for this loop */
|
|
int iCur = pLevel->iTabCur; /* The cursor of the table */
|
|
WhereTerm *pTerm; /* A single constraint term */
|
|
int j; /* Loop counter */
|
|
int regBase; /* Base register */
|
|
int nReg; /* Number of registers to allocate */
|
|
|
|
/* This module is only called on query plans that use an index. */
|
|
assert( pLevel->plan.wsFlags & WHERE_INDEXED );
|
|
pIdx = pLevel->plan.u.pIdx;
|
|
|
|
/* Figure out how many memory cells we will need then allocate them.
|
|
*/
|
|
regBase = pParse->nMem + 1;
|
|
nReg = pLevel->plan.nEq + nExtraReg;
|
|
pParse->nMem += nReg;
|
|
|
|
/* Evaluate the equality constraints
|
|
*/
|
|
assert( pIdx->nColumn>=nEq );
|
|
for(j=0; j<nEq; j++){
|
|
int r1;
|
|
int k = pIdx->aiColumn[j];
|
|
pTerm = findTerm(pWC, iCur, k, notReady, pLevel->plan.wsFlags, pIdx);
|
|
if( NEVER(pTerm==0) ) break;
|
|
assert( (pTerm->wtFlags & TERM_CODED)==0 );
|
|
r1 = codeEqualityTerm(pParse, pTerm, pLevel, regBase+j);
|
|
if( r1!=regBase+j ){
|
|
if( nReg==1 ){
|
|
sqlite3ReleaseTempReg(pParse, regBase);
|
|
regBase = r1;
|
|
}else{
|
|
sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
|
|
}
|
|
}
|
|
testcase( pTerm->eOperator & WO_ISNULL );
|
|
testcase( pTerm->eOperator & WO_IN );
|
|
if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
|
|
sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
|
|
}
|
|
}
|
|
return regBase;
|
|
}
|
|
|
|
/*
|
|
** Generate code for the start of the iLevel-th loop in the WHERE clause
|
|
** implementation described by pWInfo.
|
|
*/
|
|
static Bitmask codeOneLoopStart(
|
|
WhereInfo *pWInfo, /* Complete information about the WHERE clause */
|
|
int iLevel, /* Which level of pWInfo->a[] should be coded */
|
|
u16 wctrlFlags, /* One of the WHERE_* flags defined in sqliteInt.h */
|
|
Bitmask notReady /* Which tables are currently available */
|
|
){
|
|
int j, k; /* Loop counters */
|
|
int iCur; /* The VDBE cursor for the table */
|
|
int addrNxt; /* Where to jump to continue with the next IN case */
|
|
int omitTable; /* True if we use the index only */
|
|
int bRev; /* True if we need to scan in reverse order */
|
|
WhereLevel *pLevel; /* The where level to be coded */
|
|
WhereClause *pWC; /* Decomposition of the entire WHERE clause */
|
|
WhereTerm *pTerm; /* A WHERE clause term */
|
|
Parse *pParse; /* Parsing context */
|
|
Vdbe *v; /* The prepared stmt under constructions */
|
|
struct SrcList_item *pTabItem; /* FROM clause term being coded */
|
|
int addrBrk; /* Jump here to break out of the loop */
|
|
int addrCont; /* Jump here to continue with next cycle */
|
|
int iRowidReg = 0; /* Rowid is stored in this register, if not zero */
|
|
int iReleaseReg = 0; /* Temp register to free before returning */
|
|
|
|
pParse = pWInfo->pParse;
|
|
v = pParse->pVdbe;
|
|
pWC = pWInfo->pWC;
|
|
pLevel = &pWInfo->a[iLevel];
|
|
pTabItem = &pWInfo->pTabList->a[pLevel->iFrom];
|
|
iCur = pTabItem->iCursor;
|
|
bRev = (pLevel->plan.wsFlags & WHERE_REVERSE)!=0;
|
|
omitTable = (pLevel->plan.wsFlags & WHERE_IDX_ONLY)!=0
|
|
&& (wctrlFlags & WHERE_FORCE_TABLE)==0;
|
|
|
|
/* Create labels for the "break" and "continue" instructions
|
|
** for the current loop. Jump to addrBrk to break out of a loop.
|
|
** Jump to cont to go immediately to the next iteration of the
|
|
** loop.
|
|
**
|
|
** When there is an IN operator, we also have a "addrNxt" label that
|
|
** means to continue with the next IN value combination. When
|
|
** there are no IN operators in the constraints, the "addrNxt" label
|
|
** is the same as "addrBrk".
|
|
*/
|
|
addrBrk = pLevel->addrBrk = pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
|
|
addrCont = pLevel->addrCont = sqlite3VdbeMakeLabel(v);
|
|
|
|
/* If this is the right table of a LEFT OUTER JOIN, allocate and
|
|
** initialize a memory cell that records if this table matches any
|
|
** row of the left table of the join.
|
|
*/
|
|
if( pLevel->iFrom>0 && (pTabItem[0].jointype & JT_LEFT)!=0 ){
|
|
pLevel->iLeftJoin = ++pParse->nMem;
|
|
sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
|
|
VdbeComment((v, "init LEFT JOIN no-match flag"));
|
|
}
|
|
|
|
#ifndef SQLITE_OMIT_VIRTUALTABLE
|
|
if( (pLevel->plan.wsFlags & WHERE_VIRTUALTABLE)!=0 ){
|
|
/* Case 0: The table is a virtual-table. Use the VFilter and VNext
|
|
** to access the data.
|
|
*/
|
|
int iReg; /* P3 Value for OP_VFilter */
|
|
sqlite3_index_info *pVtabIdx = pLevel->plan.u.pVtabIdx;
|
|
int nConstraint = pVtabIdx->nConstraint;
|
|
struct sqlite3_index_constraint_usage *aUsage =
|
|
pVtabIdx->aConstraintUsage;
|
|
const struct sqlite3_index_constraint *aConstraint =
|
|
pVtabIdx->aConstraint;
|
|
|
|
iReg = sqlite3GetTempRange(pParse, nConstraint+2);
|
|
for(j=1; j<=nConstraint; j++){
|
|
for(k=0; k<nConstraint; k++){
|
|
if( aUsage[k].argvIndex==j ){
|
|
int iTerm = aConstraint[k].iTermOffset;
|
|
sqlite3ExprCode(pParse, pWC->a[iTerm].pExpr->pRight, iReg+j+1);
|
|
break;
|
|
}
|
|
}
|
|
if( k==nConstraint ) break;
|
|
}
|
|
sqlite3VdbeAddOp2(v, OP_Integer, pVtabIdx->idxNum, iReg);
|
|
sqlite3VdbeAddOp2(v, OP_Integer, j-1, iReg+1);
|
|
sqlite3VdbeAddOp4(v, OP_VFilter, iCur, addrBrk, iReg, pVtabIdx->idxStr,
|
|
pVtabIdx->needToFreeIdxStr ? P4_MPRINTF : P4_STATIC);
|
|
pVtabIdx->needToFreeIdxStr = 0;
|
|
for(j=0; j<nConstraint; j++){
|
|
if( aUsage[j].omit ){
|
|
int iTerm = aConstraint[j].iTermOffset;
|
|
disableTerm(pLevel, &pWC->a[iTerm]);
|
|
}
|
|
}
|
|
pLevel->op = OP_VNext;
|
|
pLevel->p1 = iCur;
|
|
pLevel->p2 = sqlite3VdbeCurrentAddr(v);
|
|
sqlite3ReleaseTempRange(pParse, iReg, nConstraint+2);
|
|
}else
|
|
#endif /* SQLITE_OMIT_VIRTUALTABLE */
|
|
|
|
if( pLevel->plan.wsFlags & WHERE_ROWID_EQ ){
|
|
/* Case 1: We can directly reference a single row using an
|
|
** equality comparison against the ROWID field. Or
|
|
** we reference multiple rows using a "rowid IN (...)"
|
|
** construct.
|
|
*/
|
|
iReleaseReg = sqlite3GetTempReg(pParse);
|
|
pTerm = findTerm(pWC, iCur, -1, notReady, WO_EQ|WO_IN, 0);
|
|
assert( pTerm!=0 );
|
|
assert( pTerm->pExpr!=0 );
|
|
assert( pTerm->leftCursor==iCur );
|
|
assert( omitTable==0 );
|
|
iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, iReleaseReg);
|
|
addrNxt = pLevel->addrNxt;
|
|
sqlite3VdbeAddOp2(v, OP_MustBeInt, iRowidReg, addrNxt);
|
|
sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addrNxt, iRowidReg);
|
|
sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
|
|
VdbeComment((v, "pk"));
|
|
pLevel->op = OP_Noop;
|
|
}else if( pLevel->plan.wsFlags & WHERE_ROWID_RANGE ){
|
|
/* Case 2: We have an inequality comparison against the ROWID field.
|
|
*/
|
|
int testOp = OP_Noop;
|
|
int start;
|
|
int memEndValue = 0;
|
|
WhereTerm *pStart, *pEnd;
|
|
|
|
assert( omitTable==0 );
|
|
pStart = findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0);
|
|
pEnd = findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE, 0);
|
|
if( bRev ){
|
|
pTerm = pStart;
|
|
pStart = pEnd;
|
|
pEnd = pTerm;
|
|
}
|
|
if( pStart ){
|
|
Expr *pX; /* The expression that defines the start bound */
|
|
int r1, rTemp; /* Registers for holding the start boundary */
|
|
|
|
/* The following constant maps TK_xx codes into corresponding
|
|
** seek opcodes. It depends on a particular ordering of TK_xx
|
|
*/
|
|
const u8 aMoveOp[] = {
|
|
/* TK_GT */ OP_SeekGt,
|
|
/* TK_LE */ OP_SeekLe,
|
|
/* TK_LT */ OP_SeekLt,
|
|
/* TK_GE */ OP_SeekGe
|
|
};
|
|
assert( TK_LE==TK_GT+1 ); /* Make sure the ordering.. */
|
|
assert( TK_LT==TK_GT+2 ); /* ... of the TK_xx values... */
|
|
assert( TK_GE==TK_GT+3 ); /* ... is correcct. */
|
|
|
|
pX = pStart->pExpr;
|
|
assert( pX!=0 );
|
|
assert( pStart->leftCursor==iCur );
|
|
r1 = sqlite3ExprCodeTemp(pParse, pX->pRight, &rTemp);
|
|
sqlite3VdbeAddOp3(v, aMoveOp[pX->op-TK_GT], iCur, addrBrk, r1);
|
|
VdbeComment((v, "pk"));
|
|
sqlite3ExprCacheAffinityChange(pParse, r1, 1);
|
|
sqlite3ReleaseTempReg(pParse, rTemp);
|
|
disableTerm(pLevel, pStart);
|
|
}else{
|
|
sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, addrBrk);
|
|
}
|
|
if( pEnd ){
|
|
Expr *pX;
|
|
pX = pEnd->pExpr;
|
|
assert( pX!=0 );
|
|
assert( pEnd->leftCursor==iCur );
|
|
memEndValue = ++pParse->nMem;
|
|
sqlite3ExprCode(pParse, pX->pRight, memEndValue);
|
|
if( pX->op==TK_LT || pX->op==TK_GT ){
|
|
testOp = bRev ? OP_Le : OP_Ge;
|
|
}else{
|
|
testOp = bRev ? OP_Lt : OP_Gt;
|
|
}
|
|
disableTerm(pLevel, pEnd);
|
|
}
|
|
start = sqlite3VdbeCurrentAddr(v);
|
|
pLevel->op = bRev ? OP_Prev : OP_Next;
|
|
pLevel->p1 = iCur;
|
|
pLevel->p2 = start;
|
|
pLevel->p5 = (pStart==0 && pEnd==0) ?1:0;
|
|
if( testOp!=OP_Noop ){
|
|
iRowidReg = iReleaseReg = sqlite3GetTempReg(pParse);
|
|
sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg);
|
|
sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
|
|
sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, iRowidReg);
|
|
sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL);
|
|
}
|
|
}else if( pLevel->plan.wsFlags & (WHERE_COLUMN_RANGE|WHERE_COLUMN_EQ) ){
|
|
/* Case 3: A scan using an index.
|
|
**
|
|
** The WHERE clause may contain zero or more equality
|
|
** terms ("==" or "IN" operators) that refer to the N
|
|
** left-most columns of the index. It may also contain
|
|
** inequality constraints (>, <, >= or <=) on the indexed
|
|
** column that immediately follows the N equalities. Only
|
|
** the right-most column can be an inequality - the rest must
|
|
** use the "==" and "IN" operators. For example, if the
|
|
** index is on (x,y,z), then the following clauses are all
|
|
** optimized:
|
|
**
|
|
** x=5
|
|
** x=5 AND y=10
|
|
** x=5 AND y<10
|
|
** x=5 AND y>5 AND y<10
|
|
** x=5 AND y=5 AND z<=10
|
|
**
|
|
** The z<10 term of the following cannot be used, only
|
|
** the x=5 term:
|
|
**
|
|
** x=5 AND z<10
|
|
**
|
|
** N may be zero if there are inequality constraints.
|
|
** If there are no inequality constraints, then N is at
|
|
** least one.
|
|
**
|
|
** This case is also used when there are no WHERE clause
|
|
** constraints but an index is selected anyway, in order
|
|
** to force the output order to conform to an ORDER BY.
|
|
*/
|
|
int aStartOp[] = {
|
|
0,
|
|
0,
|
|
OP_Rewind, /* 2: (!start_constraints && startEq && !bRev) */
|
|
OP_Last, /* 3: (!start_constraints && startEq && bRev) */
|
|
OP_SeekGt, /* 4: (start_constraints && !startEq && !bRev) */
|
|
OP_SeekLt, /* 5: (start_constraints && !startEq && bRev) */
|
|
OP_SeekGe, /* 6: (start_constraints && startEq && !bRev) */
|
|
OP_SeekLe /* 7: (start_constraints && startEq && bRev) */
|
|
};
|
|
int aEndOp[] = {
|
|
OP_Noop, /* 0: (!end_constraints) */
|
|
OP_IdxGE, /* 1: (end_constraints && !bRev) */
|
|
OP_IdxLT /* 2: (end_constraints && bRev) */
|
|
};
|
|
int nEq = pLevel->plan.nEq;
|
|
int isMinQuery = 0; /* If this is an optimized SELECT min(x).. */
|
|
int regBase; /* Base register holding constraint values */
|
|
int r1; /* Temp register */
|
|
WhereTerm *pRangeStart = 0; /* Inequality constraint at range start */
|
|
WhereTerm *pRangeEnd = 0; /* Inequality constraint at range end */
|
|
int startEq; /* True if range start uses ==, >= or <= */
|
|
int endEq; /* True if range end uses ==, >= or <= */
|
|
int start_constraints; /* Start of range is constrained */
|
|
int nConstraint; /* Number of constraint terms */
|
|
Index *pIdx; /* The index we will be using */
|
|
int iIdxCur; /* The VDBE cursor for the index */
|
|
int nExtraReg = 0; /* Number of extra registers needed */
|
|
int op; /* Instruction opcode */
|
|
|
|
pIdx = pLevel->plan.u.pIdx;
|
|
iIdxCur = pLevel->iIdxCur;
|
|
k = pIdx->aiColumn[nEq]; /* Column for inequality constraints */
|
|
|
|
/* If this loop satisfies a sort order (pOrderBy) request that
|
|
** was passed to this function to implement a "SELECT min(x) ..."
|
|
** query, then the caller will only allow the loop to run for
|
|
** a single iteration. This means that the first row returned
|
|
** should not have a NULL value stored in 'x'. If column 'x' is
|
|
** the first one after the nEq equality constraints in the index,
|
|
** this requires some special handling.
|
|
*/
|
|
if( (wctrlFlags&WHERE_ORDERBY_MIN)!=0
|
|
&& (pLevel->plan.wsFlags&WHERE_ORDERBY)
|
|
&& (pIdx->nColumn>nEq)
|
|
){
|
|
/* assert( pOrderBy->nExpr==1 ); */
|
|
/* assert( pOrderBy->a[0].pExpr->iColumn==pIdx->aiColumn[nEq] ); */
|
|
isMinQuery = 1;
|
|
nExtraReg = 1;
|
|
}
|
|
|
|
/* Find any inequality constraint terms for the start and end
|
|
** of the range.
|
|
*/
|
|
if( pLevel->plan.wsFlags & WHERE_TOP_LIMIT ){
|
|
pRangeEnd = findTerm(pWC, iCur, k, notReady, (WO_LT|WO_LE), pIdx);
|
|
nExtraReg = 1;
|
|
}
|
|
if( pLevel->plan.wsFlags & WHERE_BTM_LIMIT ){
|
|
pRangeStart = findTerm(pWC, iCur, k, notReady, (WO_GT|WO_GE), pIdx);
|
|
nExtraReg = 1;
|
|
}
|
|
|
|
/* Generate code to evaluate all constraint terms using == or IN
|
|
** and store the values of those terms in an array of registers
|
|
** starting at regBase.
|
|
*/
|
|
regBase = codeAllEqualityTerms(pParse, pLevel, pWC, notReady, nExtraReg);
|
|
addrNxt = pLevel->addrNxt;
|
|
|
|
|
|
/* If we are doing a reverse order scan on an ascending index, or
|
|
** a forward order scan on a descending index, interchange the
|
|
** start and end terms (pRangeStart and pRangeEnd).
|
|
*/
|
|
if( bRev==(pIdx->aSortOrder[nEq]==SQLITE_SO_ASC) ){
|
|
SWAP(WhereTerm *, pRangeEnd, pRangeStart);
|
|
}
|
|
|
|
testcase( pRangeStart && pRangeStart->eOperator & WO_LE );
|
|
testcase( pRangeStart && pRangeStart->eOperator & WO_GE );
|
|
testcase( pRangeEnd && pRangeEnd->eOperator & WO_LE );
|
|
testcase( pRangeEnd && pRangeEnd->eOperator & WO_GE );
|
|
startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE);
|
|
endEq = !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE);
|
|
start_constraints = pRangeStart || nEq>0;
|
|
|
|
/* Seek the index cursor to the start of the range. */
|
|
nConstraint = nEq;
|
|
if( pRangeStart ){
|
|
sqlite3ExprCode(pParse, pRangeStart->pExpr->pRight, regBase+nEq);
|
|
sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
|
|
nConstraint++;
|
|
}else if( isMinQuery ){
|
|
sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
|
|
nConstraint++;
|
|
startEq = 0;
|
|
start_constraints = 1;
|
|
}
|
|
codeApplyAffinity(pParse, regBase, nConstraint, pIdx);
|
|
op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
|
|
assert( op!=0 );
|
|
testcase( op==OP_Rewind );
|
|
testcase( op==OP_Last );
|
|
testcase( op==OP_SeekGt );
|
|
testcase( op==OP_SeekGe );
|
|
testcase( op==OP_SeekLe );
|
|
testcase( op==OP_SeekLt );
|
|
sqlite3VdbeAddOp4(v, op, iIdxCur, addrNxt, regBase,
|
|
SQLITE_INT_TO_PTR(nConstraint), P4_INT32);
|
|
|
|
/* Load the value for the inequality constraint at the end of the
|
|
** range (if any).
|
|
*/
|
|
nConstraint = nEq;
|
|
if( pRangeEnd ){
|
|
sqlite3ExprCacheRemove(pParse, regBase+nEq);
|
|
sqlite3ExprCode(pParse, pRangeEnd->pExpr->pRight, regBase+nEq);
|
|
sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
|
|
codeApplyAffinity(pParse, regBase, nEq+1, pIdx);
|
|
nConstraint++;
|
|
}
|
|
|
|
/* Top of the loop body */
|
|
pLevel->p2 = sqlite3VdbeCurrentAddr(v);
|
|
|
|
/* Check if the index cursor is past the end of the range. */
|
|
op = aEndOp[(pRangeEnd || nEq) * (1 + bRev)];
|
|
testcase( op==OP_Noop );
|
|
testcase( op==OP_IdxGE );
|
|
testcase( op==OP_IdxLT );
|
|
if( op!=OP_Noop ){
|
|
sqlite3VdbeAddOp4(v, op, iIdxCur, addrNxt, regBase,
|
|
SQLITE_INT_TO_PTR(nConstraint), P4_INT32);
|
|
sqlite3VdbeChangeP5(v, endEq!=bRev ?1:0);
|
|
}
|
|
|
|
/* If there are inequality constraints, check that the value
|
|
** of the table column that the inequality contrains is not NULL.
|
|
** If it is, jump to the next iteration of the loop.
|
|
*/
|
|
r1 = sqlite3GetTempReg(pParse);
|
|
testcase( pLevel->plan.wsFlags & WHERE_BTM_LIMIT );
|
|
testcase( pLevel->plan.wsFlags & WHERE_TOP_LIMIT );
|
|
if( pLevel->plan.wsFlags & (WHERE_BTM_LIMIT|WHERE_TOP_LIMIT) ){
|
|
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, nEq, r1);
|
|
sqlite3VdbeAddOp2(v, OP_IsNull, r1, addrCont);
|
|
}
|
|
sqlite3ReleaseTempReg(pParse, r1);
|
|
|
|
/* Seek the table cursor, if required */
|
|
disableTerm(pLevel, pRangeStart);
|
|
disableTerm(pLevel, pRangeEnd);
|
|
if( !omitTable ){
|
|
iRowidReg = iReleaseReg = sqlite3GetTempReg(pParse);
|
|
sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, iRowidReg);
|
|
sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
|
|
sqlite3VdbeAddOp2(v, OP_Seek, iCur, iRowidReg); /* Deferred seek */
|
|
}
|
|
|
|
/* Record the instruction used to terminate the loop. Disable
|
|
** WHERE clause terms made redundant by the index range scan.
|
|
*/
|
|
pLevel->op = bRev ? OP_Prev : OP_Next;
|
|
pLevel->p1 = iIdxCur;
|
|
}else
|
|
|
|
#ifndef SQLITE_OMIT_OR_OPTIMIZATION
|
|
if( pLevel->plan.wsFlags & WHERE_MULTI_OR ){
|
|
/* Case 4: Two or more separately indexed terms connected by OR
|
|
**
|
|
** Example:
|
|
**
|
|
** CREATE TABLE t1(a,b,c,d);
|
|
** CREATE INDEX i1 ON t1(a);
|
|
** CREATE INDEX i2 ON t1(b);
|
|
** CREATE INDEX i3 ON t1(c);
|
|
**
|
|
** SELECT * FROM t1 WHERE a=5 OR b=7 OR (c=11 AND d=13)
|
|
**
|
|
** In the example, there are three indexed terms connected by OR.
|
|
** The top of the loop looks like this:
|
|
**
|
|
** Null 1 # Zero the rowset in reg 1
|
|
**
|
|
** Then, for each indexed term, the following. The arguments to
|
|
** RowSetTest are such that the rowid of the current row is inserted
|
|
** into the RowSet. If it is already present, control skips the
|
|
** Gosub opcode and jumps straight to the code generated by WhereEnd().
|
|
**
|
|
** sqlite3WhereBegin(<term>)
|
|
** RowSetTest # Insert rowid into rowset
|
|
** Gosub 2 A
|
|
** sqlite3WhereEnd()
|
|
**
|
|
** Following the above, code to terminate the loop. Label A, the target
|
|
** of the Gosub above, jumps to the instruction right after the Goto.
|
|
**
|
|
** Null 1 # Zero the rowset in reg 1
|
|
** Goto B # The loop is finished.
|
|
**
|
|
** A: <loop body> # Return data, whatever.
|
|
**
|
|
** Return 2 # Jump back to the Gosub
|
|
**
|
|
** B: <after the loop>
|
|
**
|
|
*/
|
|
WhereClause *pOrWc; /* The OR-clause broken out into subterms */
|
|
WhereTerm *pFinal; /* Final subterm within the OR-clause. */
|
|
SrcList oneTab; /* Shortened table list */
|
|
|
|
int regReturn = ++pParse->nMem; /* Register used with OP_Gosub */
|
|
int regRowset; /* Register for RowSet object */
|
|
int regRowid; /* Register holding rowid */
|
|
int iLoopBody = sqlite3VdbeMakeLabel(v); /* Start of loop body */
|
|
int iRetInit; /* Address of regReturn init */
|
|
int ii;
|
|
|
|
pTerm = pLevel->plan.u.pTerm;
|
|
assert( pTerm!=0 );
|
|
assert( pTerm->eOperator==WO_OR );
|
|
assert( (pTerm->wtFlags & TERM_ORINFO)!=0 );
|
|
pOrWc = &pTerm->u.pOrInfo->wc;
|
|
pFinal = &pOrWc->a[pOrWc->nTerm-1];
|
|
|
|
/* Set up a SrcList containing just the table being scanned by this loop. */
|
|
oneTab.nSrc = 1;
|
|
oneTab.nAlloc = 1;
|
|
oneTab.a[0] = *pTabItem;
|
|
|
|
/* Initialize the rowset register to contain NULL. An SQL NULL is
|
|
** equivalent to an empty rowset.
|
|
**
|
|
** Also initialize regReturn to contain the address of the instruction
|
|
** immediately following the OP_Return at the bottom of the loop. This
|
|
** is required in a few obscure LEFT JOIN cases where control jumps
|
|
** over the top of the loop into the body of it. In this case the
|
|
** correct response for the end-of-loop code (the OP_Return) is to
|
|
** fall through to the next instruction, just as an OP_Next does if
|
|
** called on an uninitialized cursor.
|
|
*/
|
|
if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
|
|
regRowset = ++pParse->nMem;
|
|
regRowid = ++pParse->nMem;
|
|
sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset);
|
|
}
|
|
iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);
|
|
|
|
for(ii=0; ii<pOrWc->nTerm; ii++){
|
|
WhereTerm *pOrTerm = &pOrWc->a[ii];
|
|
if( pOrTerm->leftCursor==iCur || pOrTerm->eOperator==WO_AND ){
|
|
WhereInfo *pSubWInfo; /* Info for single OR-term scan */
|
|
|
|
/* Loop through table entries that match term pOrTerm. */
|
|
pSubWInfo = sqlite3WhereBegin(pParse, &oneTab, pOrTerm->pExpr, 0,
|
|
WHERE_OMIT_OPEN | WHERE_OMIT_CLOSE | WHERE_FORCE_TABLE);
|
|
if( pSubWInfo ){
|
|
if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
|
|
int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
|
|
int r;
|
|
r = sqlite3ExprCodeGetColumn(pParse, pTabItem->pTab, -1, iCur,
|
|
regRowid, 0);
|
|
sqlite3VdbeAddOp4(v, OP_RowSetTest, regRowset,
|
|
sqlite3VdbeCurrentAddr(v)+2,
|
|
r, SQLITE_INT_TO_PTR(iSet), P4_INT32);
|
|
}
|
|
sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody);
|
|
|
|
/* Finish the loop through table entries that match term pOrTerm. */
|
|
sqlite3WhereEnd(pSubWInfo);
|
|
}
|
|
}
|
|
}
|
|
sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
|
|
/* sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset); */
|
|
sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk);
|
|
sqlite3VdbeResolveLabel(v, iLoopBody);
|
|
|
|
pLevel->op = OP_Return;
|
|
pLevel->p1 = regReturn;
|
|
disableTerm(pLevel, pTerm);
|
|
}else
|
|
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
|
|
|
|
{
|
|
/* Case 5: There is no usable index. We must do a complete
|
|
** scan of the entire table.
|
|
*/
|
|
static const u8 aStep[] = { OP_Next, OP_Prev };
|
|
static const u8 aStart[] = { OP_Rewind, OP_Last };
|
|
assert( bRev==0 || bRev==1 );
|
|
assert( omitTable==0 );
|
|
pLevel->op = aStep[bRev];
|
|
pLevel->p1 = iCur;
|
|
pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk);
|
|
pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
|
|
}
|
|
notReady &= ~getMask(pWC->pMaskSet, iCur);
|
|
|
|
/* Insert code to test every subexpression that can be completely
|
|
** computed using the current set of tables.
|
|
*/
|
|
k = 0;
|
|
for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
|
|
Expr *pE;
|
|
testcase( pTerm->wtFlags & TERM_VIRTUAL );
|
|
testcase( pTerm->wtFlags & TERM_CODED );
|
|
if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
|
|
if( (pTerm->prereqAll & notReady)!=0 ) continue;
|
|
pE = pTerm->pExpr;
|
|
assert( pE!=0 );
|
|
if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
|
|
continue;
|
|
}
|
|
sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL);
|
|
k = 1;
|
|
pTerm->wtFlags |= TERM_CODED;
|
|
}
|
|
|
|
/* For a LEFT OUTER JOIN, generate code that will record the fact that
|
|
** at least one row of the right table has matched the left table.
|
|
*/
|
|
if( pLevel->iLeftJoin ){
|
|
pLevel->addrFirst = sqlite3VdbeCurrentAddr(v);
|
|
sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->iLeftJoin);
|
|
VdbeComment((v, "record LEFT JOIN hit"));
|
|
sqlite3ExprCacheClear(pParse);
|
|
for(pTerm=pWC->a, j=0; j<pWC->nTerm; j++, pTerm++){
|
|
testcase( pTerm->wtFlags & TERM_VIRTUAL );
|
|
testcase( pTerm->wtFlags & TERM_CODED );
|
|
if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
|
|
if( (pTerm->prereqAll & notReady)!=0 ) continue;
|
|
assert( pTerm->pExpr );
|
|
sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL);
|
|
pTerm->wtFlags |= TERM_CODED;
|
|
}
|
|
}
|
|
sqlite3ReleaseTempReg(pParse, iReleaseReg);
|
|
|
|
return notReady;
|
|
}
|
|
|
|
#if defined(SQLITE_TEST)
|
|
/*
|
|
** The following variable holds a text description of query plan generated
|
|
** by the most recent call to sqlite3WhereBegin(). Each call to WhereBegin
|
|
** overwrites the previous. This information is used for testing and
|
|
** analysis only.
|
|
*/
|
|
char sqlite3_query_plan[BMS*2*40]; /* Text of the join */
|
|
static int nQPlan = 0; /* Next free slow in _query_plan[] */
|
|
|
|
#endif /* SQLITE_TEST */
|
|
|
|
|
|
/*
|
|
** Free a WhereInfo structure
|
|
*/
|
|
static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
|
|
if( pWInfo ){
|
|
int i;
|
|
for(i=0; i<pWInfo->nLevel; i++){
|
|
sqlite3_index_info *pInfo = pWInfo->a[i].pIdxInfo;
|
|
if( pInfo ){
|
|
/* assert( pInfo->needToFreeIdxStr==0 || db->mallocFailed ); */
|
|
if( pInfo->needToFreeIdxStr ){
|
|
sqlite3_free(pInfo->idxStr);
|
|
}
|
|
sqlite3DbFree(db, pInfo);
|
|
}
|
|
}
|
|
whereClauseClear(pWInfo->pWC);
|
|
sqlite3DbFree(db, pWInfo);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
** Generate the beginning of the loop used for WHERE clause processing.
|
|
** The return value is a pointer to an opaque structure that contains
|
|
** information needed to terminate the loop. Later, the calling routine
|
|
** should invoke sqlite3WhereEnd() with the return value of this function
|
|
** in order to complete the WHERE clause processing.
|
|
**
|
|
** If an error occurs, this routine returns NULL.
|
|
**
|
|
** The basic idea is to do a nested loop, one loop for each table in
|
|
** the FROM clause of a select. (INSERT and UPDATE statements are the
|
|
** same as a SELECT with only a single table in the FROM clause.) For
|
|
** example, if the SQL is this:
|
|
**
|
|
** SELECT * FROM t1, t2, t3 WHERE ...;
|
|
**
|
|
** Then the code generated is conceptually like the following:
|
|
**
|
|
** foreach row1 in t1 do \ Code generated
|
|
** foreach row2 in t2 do |-- by sqlite3WhereBegin()
|
|
** foreach row3 in t3 do /
|
|
** ...
|
|
** end \ Code generated
|
|
** end |-- by sqlite3WhereEnd()
|
|
** end /
|
|
**
|
|
** Note that the loops might not be nested in the order in which they
|
|
** appear in the FROM clause if a different order is better able to make
|
|
** use of indices. Note also that when the IN operator appears in
|
|
** the WHERE clause, it might result in additional nested loops for
|
|
** scanning through all values on the right-hand side of the IN.
|
|
**
|
|
** There are Btree cursors associated with each table. t1 uses cursor
|
|
** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor.
|
|
** And so forth. This routine generates code to open those VDBE cursors
|
|
** and sqlite3WhereEnd() generates the code to close them.
|
|
**
|
|
** The code that sqlite3WhereBegin() generates leaves the cursors named
|
|
** in pTabList pointing at their appropriate entries. The [...] code
|
|
** can use OP_Column and OP_Rowid opcodes on these cursors to extract
|
|
** data from the various tables of the loop.
|
|
**
|
|
** If the WHERE clause is empty, the foreach loops must each scan their
|
|
** entire tables. Thus a three-way join is an O(N^3) operation. But if
|
|
** the tables have indices and there are terms in the WHERE clause that
|
|
** refer to those indices, a complete table scan can be avoided and the
|
|
** code will run much faster. Most of the work of this routine is checking
|
|
** to see if there are indices that can be used to speed up the loop.
|
|
**
|
|
** Terms of the WHERE clause are also used to limit which rows actually
|
|
** make it to the "..." in the middle of the loop. After each "foreach",
|
|
** terms of the WHERE clause that use only terms in that loop and outer
|
|
** loops are evaluated and if false a jump is made around all subsequent
|
|
** inner loops (or around the "..." if the test occurs within the inner-
|
|
** most loop)
|
|
**
|
|
** OUTER JOINS
|
|
**
|
|
** An outer join of tables t1 and t2 is conceptally coded as follows:
|
|
**
|
|
** foreach row1 in t1 do
|
|
** flag = 0
|
|
** foreach row2 in t2 do
|
|
** start:
|
|
** ...
|
|
** flag = 1
|
|
** end
|
|
** if flag==0 then
|
|
** move the row2 cursor to a null row
|
|
** goto start
|
|
** fi
|
|
** end
|
|
**
|
|
** ORDER BY CLAUSE PROCESSING
|
|
**
|
|
** *ppOrderBy is a pointer to the ORDER BY clause of a SELECT statement,
|
|
** if there is one. If there is no ORDER BY clause or if this routine
|
|
** is called from an UPDATE or DELETE statement, then ppOrderBy is NULL.
|
|
**
|
|
** If an index can be used so that the natural output order of the table
|
|
** scan is correct for the ORDER BY clause, then that index is used and
|
|
** *ppOrderBy is set to NULL. This is an optimization that prevents an
|
|
** unnecessary sort of the result set if an index appropriate for the
|
|
** ORDER BY clause already exists.
|
|
**
|
|
** If the where clause loops cannot be arranged to provide the correct
|
|
** output order, then the *ppOrderBy is unchanged.
|
|
*/
|
|
WhereInfo *sqlite3WhereBegin(
|
|
Parse *pParse, /* The parser context */
|
|
SrcList *pTabList, /* A list of all tables to be scanned */
|
|
Expr *pWhere, /* The WHERE clause */
|
|
ExprList **ppOrderBy, /* An ORDER BY clause, or NULL */
|
|
u16 wctrlFlags /* One of the WHERE_* flags defined in sqliteInt.h */
|
|
){
|
|
int i; /* Loop counter */
|
|
int nByteWInfo; /* Num. bytes allocated for WhereInfo struct */
|
|
WhereInfo *pWInfo; /* Will become the return value of this function */
|
|
Vdbe *v = pParse->pVdbe; /* The virtual database engine */
|
|
Bitmask notReady; /* Cursors that are not yet positioned */
|
|
WhereMaskSet *pMaskSet; /* The expression mask set */
|
|
WhereClause *pWC; /* Decomposition of the WHERE clause */
|
|
struct SrcList_item *pTabItem; /* A single entry from pTabList */
|
|
WhereLevel *pLevel; /* A single level in the pWInfo list */
|
|
int iFrom; /* First unused FROM clause element */
|
|
int andFlags; /* AND-ed combination of all pWC->a[].wtFlags */
|
|
sqlite3 *db; /* Database connection */
|
|
|
|
/* The number of tables in the FROM clause is limited by the number of
|
|
** bits in a Bitmask
|
|
*/
|
|
if( pTabList->nSrc>BMS ){
|
|
sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS);
|
|
return 0;
|
|
}
|
|
|
|
/* Allocate and initialize the WhereInfo structure that will become the
|
|
** return value. A single allocation is used to store the WhereInfo
|
|
** struct, the contents of WhereInfo.a[], the WhereClause structure
|
|
** and the WhereMaskSet structure. Since WhereClause contains an 8-byte
|
|
** field (type Bitmask) it must be aligned on an 8-byte boundary on
|
|
** some architectures. Hence the ROUND8() below.
|
|
*/
|
|
db = pParse->db;
|
|
nByteWInfo = ROUND8(sizeof(WhereInfo)+(pTabList->nSrc-1)*sizeof(WhereLevel));
|
|
pWInfo = sqlite3DbMallocZero(db,
|
|
nByteWInfo +
|
|
sizeof(WhereClause) +
|
|
sizeof(WhereMaskSet)
|
|
);
|
|
if( db->mallocFailed ){
|
|
goto whereBeginError;
|
|
}
|
|
pWInfo->nLevel = pTabList->nSrc;
|
|
pWInfo->pParse = pParse;
|
|
pWInfo->pTabList = pTabList;
|
|
pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
|
|
pWInfo->pWC = pWC = (WhereClause *)&((u8 *)pWInfo)[nByteWInfo];
|
|
pWInfo->wctrlFlags = wctrlFlags;
|
|
pMaskSet = (WhereMaskSet*)&pWC[1];
|
|
|
|
/* Split the WHERE clause into separate subexpressions where each
|
|
** subexpression is separated by an AND operator.
|
|
*/
|
|
initMaskSet(pMaskSet);
|
|
whereClauseInit(pWC, pParse, pMaskSet);
|
|
sqlite3ExprCodeConstants(pParse, pWhere);
|
|
whereSplit(pWC, pWhere, TK_AND);
|
|
|
|
/* Special case: a WHERE clause that is constant. Evaluate the
|
|
** expression and either jump over all of the code or fall thru.
|
|
*/
|
|
if( pWhere && (pTabList->nSrc==0 || sqlite3ExprIsConstantNotJoin(pWhere)) ){
|
|
sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, SQLITE_JUMPIFNULL);
|
|
pWhere = 0;
|
|
}
|
|
|
|
/* Assign a bit from the bitmask to every term in the FROM clause.
|
|
**
|
|
** When assigning bitmask values to FROM clause cursors, it must be
|
|
** the case that if X is the bitmask for the N-th FROM clause term then
|
|
** the bitmask for all FROM clause terms to the left of the N-th term
|
|
** is (X-1). An expression from the ON clause of a LEFT JOIN can use
|
|
** its Expr.iRightJoinTable value to find the bitmask of the right table
|
|
** of the join. Subtracting one from the right table bitmask gives a
|
|
** bitmask for all tables to the left of the join. Knowing the bitmask
|
|
** for all tables to the left of a left join is important. Ticket #3015.
|
|
**
|
|
** Configure the WhereClause.vmask variable so that bits that correspond
|
|
** to virtual table cursors are set. This is used to selectively disable
|
|
** the OR-to-IN transformation in exprAnalyzeOrTerm(). It is not helpful
|
|
** with virtual tables.
|
|
*/
|
|
assert( pWC->vmask==0 && pMaskSet->n==0 );
|
|
for(i=0; i<pTabList->nSrc; i++){
|
|
createMask(pMaskSet, pTabList->a[i].iCursor);
|
|
if( pTabList->a[i].pTab && IsVirtual(pTabList->a[i].pTab) ){
|
|
pWC->vmask |= ((Bitmask)1 << i);
|
|
}
|
|
}
|
|
#ifndef NDEBUG
|
|
{
|
|
Bitmask toTheLeft = 0;
|
|
for(i=0; i<pTabList->nSrc; i++){
|
|
Bitmask m = getMask(pMaskSet, pTabList->a[i].iCursor);
|
|
assert( (m-1)==toTheLeft );
|
|
toTheLeft |= m;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* Analyze all of the subexpressions. Note that exprAnalyze() might
|
|
** add new virtual terms onto the end of the WHERE clause. We do not
|
|
** want to analyze these virtual terms, so start analyzing at the end
|
|
** and work forward so that the added virtual terms are never processed.
|
|
*/
|
|
exprAnalyzeAll(pTabList, pWC);
|
|
if( db->mallocFailed ){
|
|
goto whereBeginError;
|
|
}
|
|
|
|
/* Chose the best index to use for each table in the FROM clause.
|
|
**
|
|
** This loop fills in the following fields:
|
|
**
|
|
** pWInfo->a[].pIdx The index to use for this level of the loop.
|
|
** pWInfo->a[].wsFlags WHERE_xxx flags associated with pIdx
|
|
** pWInfo->a[].nEq The number of == and IN constraints
|
|
** pWInfo->a[].iFrom Which term of the FROM clause is being coded
|
|
** pWInfo->a[].iTabCur The VDBE cursor for the database table
|
|
** pWInfo->a[].iIdxCur The VDBE cursor for the index
|
|
** pWInfo->a[].pTerm When wsFlags==WO_OR, the OR-clause term
|
|
**
|
|
** This loop also figures out the nesting order of tables in the FROM
|
|
** clause.
|
|
*/
|
|
notReady = ~(Bitmask)0;
|
|
pTabItem = pTabList->a;
|
|
pLevel = pWInfo->a;
|
|
andFlags = ~0;
|
|
WHERETRACE(("*** Optimizer Start ***\n"));
|
|
for(i=iFrom=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
|
|
WhereCost bestPlan; /* Most efficient plan seen so far */
|
|
Index *pIdx; /* Index for FROM table at pTabItem */
|
|
int j; /* For looping over FROM tables */
|
|
int bestJ = 0; /* The value of j */
|
|
Bitmask m; /* Bitmask value for j or bestJ */
|
|
int once = 0; /* True when first table is seen */
|
|
|
|
memset(&bestPlan, 0, sizeof(bestPlan));
|
|
bestPlan.rCost = SQLITE_BIG_DBL;
|
|
for(j=iFrom, pTabItem=&pTabList->a[j]; j<pTabList->nSrc; j++, pTabItem++){
|
|
int doNotReorder; /* True if this table should not be reordered */
|
|
WhereCost sCost; /* Cost information from best[Virtual]Index() */
|
|
ExprList *pOrderBy; /* ORDER BY clause for index to optimize */
|
|
|
|
doNotReorder = (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0;
|
|
if( once && doNotReorder ) break;
|
|
m = getMask(pMaskSet, pTabItem->iCursor);
|
|
if( (m & notReady)==0 ){
|
|
if( j==iFrom ) iFrom++;
|
|
continue;
|
|
}
|
|
pOrderBy = ((i==0 && ppOrderBy )?*ppOrderBy:0);
|
|
|
|
assert( pTabItem->pTab );
|
|
#ifndef SQLITE_OMIT_VIRTUALTABLE
|
|
if( IsVirtual(pTabItem->pTab) ){
|
|
sqlite3_index_info **pp = &pWInfo->a[j].pIdxInfo;
|
|
bestVirtualIndex(pParse, pWC, pTabItem, notReady, pOrderBy, &sCost, pp);
|
|
}else
|
|
#endif
|
|
{
|
|
bestBtreeIndex(pParse, pWC, pTabItem, notReady, pOrderBy, &sCost);
|
|
}
|
|
if( once==0 || sCost.rCost<bestPlan.rCost ){
|
|
once = 1;
|
|
bestPlan = sCost;
|
|
bestJ = j;
|
|
}
|
|
if( doNotReorder ) break;
|
|
}
|
|
assert( once );
|
|
assert( notReady & getMask(pMaskSet, pTabList->a[bestJ].iCursor) );
|
|
WHERETRACE(("*** Optimizer selects table %d for loop %d\n", bestJ,
|
|
pLevel-pWInfo->a));
|
|
if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 ){
|
|
*ppOrderBy = 0;
|
|
}
|
|
andFlags &= bestPlan.plan.wsFlags;
|
|
pLevel->plan = bestPlan.plan;
|
|
if( bestPlan.plan.wsFlags & WHERE_INDEXED ){
|
|
pLevel->iIdxCur = pParse->nTab++;
|
|
}else{
|
|
pLevel->iIdxCur = -1;
|
|
}
|
|
notReady &= ~getMask(pMaskSet, pTabList->a[bestJ].iCursor);
|
|
pLevel->iFrom = (u8)bestJ;
|
|
|
|
/* Check that if the table scanned by this loop iteration had an
|
|
** INDEXED BY clause attached to it, that the named index is being
|
|
** used for the scan. If not, then query compilation has failed.
|
|
** Return an error.
|
|
*/
|
|
pIdx = pTabList->a[bestJ].pIndex;
|
|
if( pIdx ){
|
|
if( (bestPlan.plan.wsFlags & WHERE_INDEXED)==0 ){
|
|
sqlite3ErrorMsg(pParse, "cannot use index: %s", pIdx->zName);
|
|
goto whereBeginError;
|
|
}else{
|
|
/* If an INDEXED BY clause is used, the bestIndex() function is
|
|
** guaranteed to find the index specified in the INDEXED BY clause
|
|
** if it find an index at all. */
|
|
assert( bestPlan.plan.u.pIdx==pIdx );
|
|
}
|
|
}
|
|
}
|
|
WHERETRACE(("*** Optimizer Finished ***\n"));
|
|
if( pParse->nErr || db->mallocFailed ){
|
|
goto whereBeginError;
|
|
}
|
|
|
|
/* If the total query only selects a single row, then the ORDER BY
|
|
** clause is irrelevant.
|
|
*/
|
|
if( (andFlags & WHERE_UNIQUE)!=0 && ppOrderBy ){
|
|
*ppOrderBy = 0;
|
|
}
|
|
|
|
/* If the caller is an UPDATE or DELETE statement that is requesting
|
|
** to use a one-pass algorithm, determine if this is appropriate.
|
|
** The one-pass algorithm only works if the WHERE clause constraints
|
|
** the statement to update a single row.
|
|
*/
|
|
assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
|
|
if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 && (andFlags & WHERE_UNIQUE)!=0 ){
|
|
pWInfo->okOnePass = 1;
|
|
pWInfo->a[0].plan.wsFlags &= ~WHERE_IDX_ONLY;
|
|
}
|
|
|
|
/* Open all tables in the pTabList and any indices selected for
|
|
** searching those tables.
|
|
*/
|
|
sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
|
|
for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
|
|
Table *pTab; /* Table to open */
|
|
int iDb; /* Index of database containing table/index */
|
|
|
|
#ifndef SQLITE_OMIT_EXPLAIN
|
|
if( pParse->explain==2 ){
|
|
char *zMsg;
|
|
struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
|
|
zMsg = sqlite3MPrintf(db, "TABLE %s", pItem->zName);
|
|
if( pItem->zAlias ){
|
|
zMsg = sqlite3MAppendf(db, zMsg, "%s AS %s", zMsg, pItem->zAlias);
|
|
}
|
|
if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
|
|
zMsg = sqlite3MAppendf(db, zMsg, "%s WITH INDEX %s",
|
|
zMsg, pLevel->plan.u.pIdx->zName);
|
|
}else if( pLevel->plan.wsFlags & WHERE_MULTI_OR ){
|
|
zMsg = sqlite3MAppendf(db, zMsg, "%s VIA MULTI-INDEX UNION", zMsg);
|
|
}else if( pLevel->plan.wsFlags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
|
|
zMsg = sqlite3MAppendf(db, zMsg, "%s USING PRIMARY KEY", zMsg);
|
|
}
|
|
#ifndef SQLITE_OMIT_VIRTUALTABLE
|
|
else if( (pLevel->plan.wsFlags & WHERE_VIRTUALTABLE)!=0 ){
|
|
sqlite3_index_info *pVtabIdx = pLevel->plan.u.pVtabIdx;
|
|
zMsg = sqlite3MAppendf(db, zMsg, "%s VIRTUAL TABLE INDEX %d:%s", zMsg,
|
|
pVtabIdx->idxNum, pVtabIdx->idxStr);
|
|
}
|
|
#endif
|
|
if( pLevel->plan.wsFlags & WHERE_ORDERBY ){
|
|
zMsg = sqlite3MAppendf(db, zMsg, "%s ORDER BY", zMsg);
|
|
}
|
|
sqlite3VdbeAddOp4(v, OP_Explain, i, pLevel->iFrom, 0, zMsg, P4_DYNAMIC);
|
|
}
|
|
#endif /* SQLITE_OMIT_EXPLAIN */
|
|
pTabItem = &pTabList->a[pLevel->iFrom];
|
|
pTab = pTabItem->pTab;
|
|
iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
|
|
if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ) continue;
|
|
#ifndef SQLITE_OMIT_VIRTUALTABLE
|
|
if( (pLevel->plan.wsFlags & WHERE_VIRTUALTABLE)!=0 ){
|
|
int iCur = pTabItem->iCursor;
|
|
sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0,
|
|
(const char*)pTab->pVtab, P4_VTAB);
|
|
}else
|
|
#endif
|
|
if( (pLevel->plan.wsFlags & WHERE_IDX_ONLY)==0
|
|
&& (wctrlFlags & WHERE_OMIT_OPEN)==0 ){
|
|
int op = pWInfo->okOnePass ? OP_OpenWrite : OP_OpenRead;
|
|
sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
|
|
if( !pWInfo->okOnePass && pTab->nCol<BMS ){
|
|
Bitmask b = pTabItem->colUsed;
|
|
int n = 0;
|
|
for(; b; b=b>>1, n++){}
|
|
sqlite3VdbeChangeP4(v, sqlite3VdbeCurrentAddr(v)-1, SQLITE_INT_TO_PTR(n), P4_INT32);
|
|
assert( n<=pTab->nCol );
|
|
}
|
|
}else{
|
|
sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
|
|
}
|
|
pLevel->iTabCur = pTabItem->iCursor;
|
|
if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
|
|
Index *pIx = pLevel->plan.u.pIdx;
|
|
KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx);
|
|
int iIdxCur = pLevel->iIdxCur;
|
|
assert( pIx->pSchema==pTab->pSchema );
|
|
assert( iIdxCur>=0 );
|
|
sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIx->tnum, iDb,
|
|
(char*)pKey, P4_KEYINFO_HANDOFF);
|
|
VdbeComment((v, "%s", pIx->zName));
|
|
}
|
|
sqlite3CodeVerifySchema(pParse, iDb);
|
|
}
|
|
pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
|
|
|
|
/* Generate the code to do the search. Each iteration of the for
|
|
** loop below generates code for a single nested loop of the VM
|
|
** program.
|
|
*/
|
|
notReady = ~(Bitmask)0;
|
|
for(i=0; i<pTabList->nSrc; i++){
|
|
notReady = codeOneLoopStart(pWInfo, i, wctrlFlags, notReady);
|
|
pWInfo->iContinue = pWInfo->a[i].addrCont;
|
|
}
|
|
|
|
#ifdef SQLITE_TEST /* For testing and debugging use only */
|
|
/* Record in the query plan information about the current table
|
|
** and the index used to access it (if any). If the table itself
|
|
** is not used, its name is just '{}'. If no index is used
|
|
** the index is listed as "{}". If the primary key is used the
|
|
** index name is '*'.
|
|
*/
|
|
for(i=0; i<pTabList->nSrc; i++){
|
|
char *z;
|
|
int n;
|
|
pLevel = &pWInfo->a[i];
|
|
pTabItem = &pTabList->a[pLevel->iFrom];
|
|
z = pTabItem->zAlias;
|
|
if( z==0 ) z = pTabItem->pTab->zName;
|
|
n = sqlite3Strlen30(z);
|
|
if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){
|
|
if( pLevel->plan.wsFlags & WHERE_IDX_ONLY ){
|
|
memcpy(&sqlite3_query_plan[nQPlan], "{}", 2);
|
|
nQPlan += 2;
|
|
}else{
|
|
memcpy(&sqlite3_query_plan[nQPlan], z, n);
|
|
nQPlan += n;
|
|
}
|
|
sqlite3_query_plan[nQPlan++] = ' ';
|
|
}
|
|
testcase( pLevel->plan.wsFlags & WHERE_ROWID_EQ );
|
|
testcase( pLevel->plan.wsFlags & WHERE_ROWID_RANGE );
|
|
if( pLevel->plan.wsFlags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
|
|
memcpy(&sqlite3_query_plan[nQPlan], "* ", 2);
|
|
nQPlan += 2;
|
|
}else if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
|
|
n = sqlite3Strlen30(pLevel->plan.u.pIdx->zName);
|
|
if( n+nQPlan < sizeof(sqlite3_query_plan)-2 ){
|
|
memcpy(&sqlite3_query_plan[nQPlan], pLevel->plan.u.pIdx->zName, n);
|
|
nQPlan += n;
|
|
sqlite3_query_plan[nQPlan++] = ' ';
|
|
}
|
|
}else{
|
|
memcpy(&sqlite3_query_plan[nQPlan], "{} ", 3);
|
|
nQPlan += 3;
|
|
}
|
|
}
|
|
while( nQPlan>0 && sqlite3_query_plan[nQPlan-1]==' ' ){
|
|
sqlite3_query_plan[--nQPlan] = 0;
|
|
}
|
|
sqlite3_query_plan[nQPlan] = 0;
|
|
nQPlan = 0;
|
|
#endif /* SQLITE_TEST // Testing and debugging use only */
|
|
|
|
/* Record the continuation address in the WhereInfo structure. Then
|
|
** clean up and return.
|
|
*/
|
|
return pWInfo;
|
|
|
|
/* Jump here if malloc fails */
|
|
whereBeginError:
|
|
whereInfoFree(db, pWInfo);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** Generate the end of the WHERE loop. See comments on
|
|
** sqlite3WhereBegin() for additional information.
|
|
*/
|
|
void sqlite3WhereEnd(WhereInfo *pWInfo){
|
|
Parse *pParse = pWInfo->pParse;
|
|
Vdbe *v = pParse->pVdbe;
|
|
int i;
|
|
WhereLevel *pLevel;
|
|
SrcList *pTabList = pWInfo->pTabList;
|
|
sqlite3 *db = pParse->db;
|
|
|
|
/* Generate loop termination code.
|
|
*/
|
|
sqlite3ExprCacheClear(pParse);
|
|
for(i=pTabList->nSrc-1; i>=0; i--){
|
|
pLevel = &pWInfo->a[i];
|
|
sqlite3VdbeResolveLabel(v, pLevel->addrCont);
|
|
if( pLevel->op!=OP_Noop ){
|
|
sqlite3VdbeAddOp2(v, pLevel->op, pLevel->p1, pLevel->p2);
|
|
sqlite3VdbeChangeP5(v, pLevel->p5);
|
|
}
|
|
if( pLevel->plan.wsFlags & WHERE_IN_ABLE && pLevel->u.in.nIn>0 ){
|
|
struct InLoop *pIn;
|
|
int j;
|
|
sqlite3VdbeResolveLabel(v, pLevel->addrNxt);
|
|
for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){
|
|
sqlite3VdbeJumpHere(v, pIn->addrInTop+1);
|
|
sqlite3VdbeAddOp2(v, OP_Next, pIn->iCur, pIn->addrInTop);
|
|
sqlite3VdbeJumpHere(v, pIn->addrInTop-1);
|
|
}
|
|
sqlite3DbFree(db, pLevel->u.in.aInLoop);
|
|
}
|
|
sqlite3VdbeResolveLabel(v, pLevel->addrBrk);
|
|
if( pLevel->iLeftJoin ){
|
|
int addr;
|
|
addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin);
|
|
sqlite3VdbeAddOp1(v, OP_NullRow, pTabList->a[i].iCursor);
|
|
if( pLevel->iIdxCur>=0 ){
|
|
sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iIdxCur);
|
|
}
|
|
if( pLevel->op==OP_Return ){
|
|
sqlite3VdbeAddOp2(v, OP_Gosub, pLevel->p1, pLevel->addrFirst);
|
|
}else{
|
|
sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrFirst);
|
|
}
|
|
sqlite3VdbeJumpHere(v, addr);
|
|
}
|
|
}
|
|
|
|
/* The "break" point is here, just past the end of the outer loop.
|
|
** Set it.
|
|
*/
|
|
sqlite3VdbeResolveLabel(v, pWInfo->iBreak);
|
|
|
|
/* Close all of the cursors that were opened by sqlite3WhereBegin.
|
|
*/
|
|
for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
|
|
struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
|
|
Table *pTab = pTabItem->pTab;
|
|
assert( pTab!=0 );
|
|
if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ) continue;
|
|
if( (pWInfo->wctrlFlags & WHERE_OMIT_CLOSE)==0 ){
|
|
if( !pWInfo->okOnePass && (pLevel->plan.wsFlags & WHERE_IDX_ONLY)==0 ){
|
|
sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
|
|
}
|
|
if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
|
|
sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
|
|
}
|
|
}
|
|
|
|
/* If this scan uses an index, make code substitutions to read data
|
|
** from the index in preference to the table. Sometimes, this means
|
|
** the table need never be read from. This is a performance boost,
|
|
** as the vdbe level waits until the table is read before actually
|
|
** seeking the table cursor to the record corresponding to the current
|
|
** position in the index.
|
|
**
|
|
** Calls to the code generator in between sqlite3WhereBegin and
|
|
** sqlite3WhereEnd will have created code that references the table
|
|
** directly. This loop scans all that code looking for opcodes
|
|
** that reference the table and converts them into opcodes that
|
|
** reference the index.
|
|
*/
|
|
if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
|
|
int k, j, last;
|
|
VdbeOp *pOp;
|
|
Index *pIdx = pLevel->plan.u.pIdx;
|
|
int useIndexOnly = pLevel->plan.wsFlags & WHERE_IDX_ONLY;
|
|
|
|
assert( pIdx!=0 );
|
|
pOp = sqlite3VdbeGetOp(v, pWInfo->iTop);
|
|
last = sqlite3VdbeCurrentAddr(v);
|
|
for(k=pWInfo->iTop; k<last; k++, pOp++){
|
|
if( pOp->p1!=pLevel->iTabCur ) continue;
|
|
if( pOp->opcode==OP_Column ){
|
|
for(j=0; j<pIdx->nColumn; j++){
|
|
if( pOp->p2==pIdx->aiColumn[j] ){
|
|
pOp->p2 = j;
|
|
pOp->p1 = pLevel->iIdxCur;
|
|
break;
|
|
}
|
|
}
|
|
assert(!useIndexOnly || j<pIdx->nColumn);
|
|
}else if( pOp->opcode==OP_Rowid ){
|
|
pOp->p1 = pLevel->iIdxCur;
|
|
pOp->opcode = OP_IdxRowid;
|
|
}else if( pOp->opcode==OP_NullRow && useIndexOnly ){
|
|
pOp->opcode = OP_Noop;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Final cleanup
|
|
*/
|
|
whereInfoFree(db, pWInfo);
|
|
return;
|
|
}
|