e883f21fe8
Files correlati : sqlite Ricompilazione Demo : [ ] Commento : Passaggio da Sqlite 2 a Sqlite 3.3.5 git-svn-id: svn://10.65.10.50/trunk@13902 c028cbd2-c16b-5b4b-a496-9718f37d4682
2137 lines
74 KiB
C
Executable File
2137 lines
74 KiB
C
Executable File
/*
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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 reponsible 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 1.2 2006-04-13 12:44:29 guy Exp $
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*/
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#include "sqliteInt.h"
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/*
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** The number of bits in a Bitmask. "BMS" means "BitMask Size".
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*/
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#define BMS (sizeof(Bitmask)*8)
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/*
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** Determine the number of elements in an array.
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*/
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#define ARRAYSIZE(X) (sizeof(X)/sizeof(X[0]))
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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 sqlite3_where_trace = 0;
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# define TRACE(X) if(sqlite3_where_trace) sqlite3DebugPrintf X
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#else
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# define TRACE(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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/*
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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 an AND operator.
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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.leftColumn record the
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** cursor number and column number for X. WhereTerm.operator 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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** prereqRight and prereqAll record sets of cursor numbers,
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** but they do so indirectly. A single ExprMaskSet 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 ExprMaskSet
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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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typedef struct WhereTerm WhereTerm;
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struct WhereTerm {
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Expr *pExpr; /* Pointer to the subexpression */
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i16 iParent; /* Disable pWC->a[iParent] when this term disabled */
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i16 leftCursor; /* Cursor number of X in "X <op> <expr>" */
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i16 leftColumn; /* Column number of X in "X <op> <expr>" */
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u16 eOperator; /* A WO_xx value describing <op> */
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u8 flags; /* 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 pRight */
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Bitmask prereqAll; /* Bitmask of tables referenced by p */
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};
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/*
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** Allowed values of WhereTerm.flags
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*/
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#define TERM_DYNAMIC 0x01 /* Need to call sqlite3ExprDelete(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_OR_OK 0x10 /* 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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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[10]; /* Initial static space for a[] */
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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 ExprMaskSet.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 ExprMaskSet 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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typedef struct ExprMaskSet ExprMaskSet;
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struct ExprMaskSet {
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int n; /* Number of assigned cursor values */
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int ix[sizeof(Bitmask)*8]; /* Cursor assigned to each bit */
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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 1
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#define WO_EQ 2
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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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/*
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** Value for flags returned by bestIndex()
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*/
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#define WHERE_ROWID_EQ 0x0001 /* rowid=EXPR or rowid IN (...) */
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#define WHERE_ROWID_RANGE 0x0002 /* rowid<EXPR and/or rowid>EXPR */
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#define WHERE_COLUMN_EQ 0x0010 /* x=EXPR or x IN (...) */
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#define WHERE_COLUMN_RANGE 0x0020 /* x<EXPR and/or x>EXPR */
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#define WHERE_COLUMN_IN 0x0040 /* x IN (...) */
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#define WHERE_TOP_LIMIT 0x0100 /* x<EXPR or x<=EXPR constraint */
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#define WHERE_BTM_LIMIT 0x0200 /* x>EXPR or x>=EXPR constraint */
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#define WHERE_IDX_ONLY 0x0800 /* Use index only - omit table */
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#define WHERE_ORDERBY 0x1000 /* Output will appear in correct order */
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#define WHERE_REVERSE 0x2000 /* Scan in reverse order */
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#define WHERE_UNIQUE 0x4000 /* Selects no more than one row */
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/*
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** Initialize a preallocated WhereClause structure.
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*/
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static void whereClauseInit(WhereClause *pWC, Parse *pParse){
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pWC->pParse = pParse;
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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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}
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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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for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
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if( a->flags & TERM_DYNAMIC ){
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sqlite3ExprDelete(a->pExpr);
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}
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}
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if( pWC->a!=pWC->aStatic ){
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sqliteFree(pWC->a);
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}
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}
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/*
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** Add a new entries to the WhereClause structure. Increase the allocated
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** space as necessary.
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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 invalided 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, int flags){
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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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pWC->a = sqliteMalloc( sizeof(pWC->a[0])*pWC->nSlot*2 );
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if( pWC->a==0 ) return 0;
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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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sqliteFree(pOld);
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}
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pWC->nSlot *= 2;
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}
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pTerm = &pWC->a[idx = pWC->nTerm];
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pWC->nTerm++;
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pTerm->pExpr = p;
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pTerm->flags = flags;
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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. This 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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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
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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(ExprMaskSet *pMaskSet, int iCursor){
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int i;
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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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** 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(ExprMaskSet *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 sqlite3ExprResolveNames() on the expression. See
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** the header comment on that routine for additional information.
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** The sqlite3ExprResolveNames() 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(ExprMaskSet*, ExprList*);
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static Bitmask exprSelectTableUsage(ExprMaskSet*, Select*);
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static Bitmask exprTableUsage(ExprMaskSet *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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mask |= exprListTableUsage(pMaskSet, p->pList);
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mask |= exprSelectTableUsage(pMaskSet, p->pSelect);
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return mask;
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}
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static Bitmask exprListTableUsage(ExprMaskSet *pMaskSet, ExprList *pList){
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int i;
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Bitmask mask = 0;
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if( pList ){
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for(i=0; i<pList->nExpr; i++){
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mask |= exprTableUsage(pMaskSet, pList->a[i].pExpr);
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}
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}
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return mask;
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}
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static Bitmask exprSelectTableUsage(ExprMaskSet *pMaskSet, Select *pS){
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Bitmask mask;
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if( pS==0 ){
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mask = 0;
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}else{
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mask = exprListTableUsage(pMaskSet, pS->pEList);
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mask |= exprListTableUsage(pMaskSet, pS->pGroupBy);
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mask |= exprListTableUsage(pMaskSet, pS->pOrderBy);
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mask |= exprTableUsage(pMaskSet, pS->pWhere);
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mask |= exprTableUsage(pMaskSet, pS->pHaving);
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}
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return mask;
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}
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/*
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** Return TRUE if the given operator is one of the operators that is
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** allowed for an indexable WHERE clause term. The allowed operators are
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** "=", "<", ">", "<=", ">=", and "IN".
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*/
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static int allowedOp(int op){
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assert( TK_GT>TK_EQ && TK_GT<TK_GE );
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assert( TK_LT>TK_EQ && TK_LT<TK_GE );
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assert( TK_LE>TK_EQ && TK_LE<TK_GE );
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assert( TK_GE==TK_EQ+4 );
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return op==TK_IN || (op>=TK_EQ && op<=TK_GE);
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}
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/*
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** Swap two objects of type T.
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*/
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#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
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/*
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** Commute a comparision operator. Expressions of the form "X op Y"
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** are converted into "Y op X".
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*/
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static void exprCommute(Expr *pExpr){
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assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
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SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl);
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SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
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if( pExpr->op>=TK_GT ){
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assert( TK_LT==TK_GT+2 );
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assert( TK_GE==TK_LE+2 );
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assert( TK_GT>TK_EQ );
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assert( TK_GT<TK_LE );
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assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
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pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;
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}
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}
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/*
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** Translate from TK_xx operator to WO_xx bitmask.
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*/
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static int operatorMask(int op){
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int c;
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assert( allowedOp(op) );
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if( op==TK_IN ){
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c = WO_IN;
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}else{
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c = WO_EQ<<(op-TK_EQ);
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}
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assert( op!=TK_IN || c==WO_IN );
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assert( op!=TK_EQ || c==WO_EQ );
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assert( op!=TK_LT || c==WO_LT );
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assert( op!=TK_LE || c==WO_LE );
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assert( op!=TK_GT || c==WO_GT );
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assert( op!=TK_GE || c==WO_GE );
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return c;
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}
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/*
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** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
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** where X is a reference to the iColumn of table iCur and <op> is one of
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** the WO_xx operator codes specified by the op parameter.
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** Return a pointer to the term. Return 0 if not found.
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*/
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static WhereTerm *findTerm(
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WhereClause *pWC, /* The WHERE clause to be searched */
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int iCur, /* Cursor number of LHS */
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int iColumn, /* Column number of LHS */
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Bitmask notReady, /* RHS must not overlap with this mask */
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u16 op, /* Mask of WO_xx values describing operator */
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Index *pIdx /* Must be compatible with this index, if not NULL */
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){
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WhereTerm *pTerm;
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int k;
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for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){
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if( pTerm->leftCursor==iCur
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&& (pTerm->prereqRight & notReady)==0
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&& pTerm->leftColumn==iColumn
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&& (pTerm->eOperator & op)!=0
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){
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if( iCur>=0 && pIdx ){
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Expr *pX = pTerm->pExpr;
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CollSeq *pColl;
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char idxaff;
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int j;
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Parse *pParse = pWC->pParse;
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idxaff = pIdx->pTable->aCol[iColumn].affinity;
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if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue;
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pColl = sqlite3ExprCollSeq(pParse, pX->pLeft);
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if( !pColl ){
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if( pX->pRight ){
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pColl = sqlite3ExprCollSeq(pParse, pX->pRight);
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}
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if( !pColl ){
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pColl = pParse->db->pDfltColl;
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}
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}
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for(j=0; j<pIdx->nColumn && pIdx->aiColumn[j]!=iColumn; j++){}
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assert( j<pIdx->nColumn );
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if( sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ) continue;
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}
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return pTerm;
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}
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}
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return 0;
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}
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/* Forward reference */
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static void exprAnalyze(SrcList*, ExprMaskSet*, WhereClause*, int);
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/*
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** Call exprAnalyze on all terms in a WHERE clause.
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**
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**
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*/
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static void exprAnalyzeAll(
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SrcList *pTabList, /* the FROM clause */
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ExprMaskSet *pMaskSet, /* table masks */
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WhereClause *pWC /* the WHERE clause to be analyzed */
|
|
){
|
|
int i;
|
|
for(i=pWC->nTerm-1; i>=0; i--){
|
|
exprAnalyze(pTabList, pMaskSet, 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(
|
|
sqlite3 *db, /* The database */
|
|
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 */
|
|
){
|
|
const char *z;
|
|
Expr *pRight, *pLeft;
|
|
ExprList *pList;
|
|
int c, cnt;
|
|
int noCase;
|
|
char wc[3];
|
|
CollSeq *pColl;
|
|
|
|
if( !sqlite3IsLikeFunction(db, pExpr, &noCase, wc) ){
|
|
return 0;
|
|
}
|
|
pList = pExpr->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 = pLeft->pColl;
|
|
if( pColl==0 ){
|
|
pColl = db->pDfltColl;
|
|
}
|
|
if( (pColl->type!=SQLITE_COLL_BINARY || noCase) &&
|
|
(pColl->type!=SQLITE_COLL_NOCASE || !noCase) ){
|
|
return 0;
|
|
}
|
|
sqlite3DequoteExpr(pRight);
|
|
z = (char *)pRight->token.z;
|
|
for(cnt=0; (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2]; cnt++){}
|
|
if( cnt==0 || 255==(u8)z[cnt] ){
|
|
return 0;
|
|
}
|
|
*pisComplete = z[cnt]==wc[0] && z[cnt+1]==0;
|
|
*pnPattern = cnt;
|
|
return 1;
|
|
}
|
|
#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
|
|
|
|
/*
|
|
** 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;
|
|
}
|
|
|
|
|
|
/*
|
|
** 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 expression of the form
|
|
** "Y <op> X" is added to the WHERE clause and analyzed separately.
|
|
*/
|
|
static void exprAnalyze(
|
|
SrcList *pSrc, /* the FROM clause */
|
|
ExprMaskSet *pMaskSet, /* table masks */
|
|
WhereClause *pWC, /* the WHERE clause */
|
|
int idxTerm /* Index of the term to be analyzed */
|
|
){
|
|
WhereTerm *pTerm = &pWC->a[idxTerm];
|
|
Expr *pExpr = pTerm->pExpr;
|
|
Bitmask prereqLeft;
|
|
Bitmask prereqAll;
|
|
int nPattern;
|
|
int isComplete;
|
|
|
|
if( sqlite3MallocFailed() ) return;
|
|
prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft);
|
|
if( pExpr->op==TK_IN ){
|
|
assert( pExpr->pRight==0 );
|
|
pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->pList)
|
|
| exprSelectTableUsage(pMaskSet, pExpr->pSelect);
|
|
}else{
|
|
pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight);
|
|
}
|
|
prereqAll = exprTableUsage(pMaskSet, pExpr);
|
|
if( ExprHasProperty(pExpr, EP_FromJoin) ){
|
|
prereqAll |= getMask(pMaskSet, pExpr->iRightJoinTable);
|
|
}
|
|
pTerm->prereqAll = prereqAll;
|
|
pTerm->leftCursor = -1;
|
|
pTerm->iParent = -1;
|
|
pTerm->eOperator = 0;
|
|
if( allowedOp(pExpr->op) && (pTerm->prereqRight & prereqLeft)==0 ){
|
|
Expr *pLeft = pExpr->pLeft;
|
|
Expr *pRight = pExpr->pRight;
|
|
if( pLeft->op==TK_COLUMN ){
|
|
pTerm->leftCursor = pLeft->iTable;
|
|
pTerm->leftColumn = pLeft->iColumn;
|
|
pTerm->eOperator = operatorMask(pExpr->op);
|
|
}
|
|
if( pRight && pRight->op==TK_COLUMN ){
|
|
WhereTerm *pNew;
|
|
Expr *pDup;
|
|
if( pTerm->leftCursor>=0 ){
|
|
int idxNew;
|
|
pDup = sqlite3ExprDup(pExpr);
|
|
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->flags |= TERM_COPIED;
|
|
}else{
|
|
pDup = pExpr;
|
|
pNew = pTerm;
|
|
}
|
|
exprCommute(pDup);
|
|
pLeft = pDup->pLeft;
|
|
pNew->leftCursor = pLeft->iTable;
|
|
pNew->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.
|
|
*/
|
|
else if( pExpr->op==TK_BETWEEN ){
|
|
ExprList *pList = pExpr->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 = sqlite3Expr(ops[i], sqlite3ExprDup(pExpr->pLeft),
|
|
sqlite3ExprDup(pList->a[i].pExpr), 0);
|
|
idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
exprAnalyze(pSrc, pMaskSet, 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)
|
|
/* Attempt to convert OR-connected terms into an IN operator so that
|
|
** they can make use of indices. Example:
|
|
**
|
|
** x = expr1 OR expr2 = x OR x = expr3
|
|
**
|
|
** is converted into
|
|
**
|
|
** x IN (expr1,expr2,expr3)
|
|
**
|
|
** This optimization must be omitted if OMIT_SUBQUERY is defined because
|
|
** the compiler for the the IN operator is part of sub-queries.
|
|
*/
|
|
else if( pExpr->op==TK_OR ){
|
|
int ok;
|
|
int i, j;
|
|
int iColumn, iCursor;
|
|
WhereClause sOr;
|
|
WhereTerm *pOrTerm;
|
|
|
|
assert( (pTerm->flags & TERM_DYNAMIC)==0 );
|
|
whereClauseInit(&sOr, pWC->pParse);
|
|
whereSplit(&sOr, pExpr, TK_OR);
|
|
exprAnalyzeAll(pSrc, pMaskSet, &sOr);
|
|
assert( sOr.nTerm>0 );
|
|
j = 0;
|
|
do{
|
|
iColumn = sOr.a[j].leftColumn;
|
|
iCursor = sOr.a[j].leftCursor;
|
|
ok = iCursor>=0;
|
|
for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){
|
|
if( pOrTerm->eOperator!=WO_EQ ){
|
|
goto or_not_possible;
|
|
}
|
|
if( pOrTerm->leftCursor==iCursor && pOrTerm->leftColumn==iColumn ){
|
|
pOrTerm->flags |= TERM_OR_OK;
|
|
}else if( (pOrTerm->flags & TERM_COPIED)!=0 ||
|
|
((pOrTerm->flags & TERM_VIRTUAL)!=0 &&
|
|
(sOr.a[pOrTerm->iParent].flags & TERM_OR_OK)!=0) ){
|
|
pOrTerm->flags &= ~TERM_OR_OK;
|
|
}else{
|
|
ok = 0;
|
|
}
|
|
}
|
|
}while( !ok && (sOr.a[j++].flags & TERM_COPIED)!=0 && j<sOr.nTerm );
|
|
if( ok ){
|
|
ExprList *pList = 0;
|
|
Expr *pNew, *pDup;
|
|
for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){
|
|
if( (pOrTerm->flags & TERM_OR_OK)==0 ) continue;
|
|
pDup = sqlite3ExprDup(pOrTerm->pExpr->pRight);
|
|
pList = sqlite3ExprListAppend(pList, pDup, 0);
|
|
}
|
|
pDup = sqlite3Expr(TK_COLUMN, 0, 0, 0);
|
|
if( pDup ){
|
|
pDup->iTable = iCursor;
|
|
pDup->iColumn = iColumn;
|
|
}
|
|
pNew = sqlite3Expr(TK_IN, pDup, 0, 0);
|
|
if( pNew ){
|
|
int idxNew;
|
|
transferJoinMarkings(pNew, pExpr);
|
|
pNew->pList = pList;
|
|
idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
exprAnalyze(pSrc, pMaskSet, pWC, idxNew);
|
|
pTerm = &pWC->a[idxTerm];
|
|
pWC->a[idxNew].iParent = idxTerm;
|
|
pTerm->nChild = 1;
|
|
}else{
|
|
sqlite3ExprListDelete(pList);
|
|
}
|
|
}
|
|
or_not_possible:
|
|
whereClauseClear(&sOr);
|
|
}
|
|
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
|
|
|
|
#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
|
|
/* Add constraints to reduce the search space on a LIKE or GLOB
|
|
** operator.
|
|
*/
|
|
if( isLikeOrGlob(pWC->pParse->db, pExpr, &nPattern, &isComplete) ){
|
|
Expr *pLeft, *pRight;
|
|
Expr *pStr1, *pStr2;
|
|
Expr *pNewExpr1, *pNewExpr2;
|
|
int idxNew1, idxNew2;
|
|
|
|
pLeft = pExpr->pList->a[1].pExpr;
|
|
pRight = pExpr->pList->a[0].pExpr;
|
|
pStr1 = sqlite3Expr(TK_STRING, 0, 0, 0);
|
|
if( pStr1 ){
|
|
sqlite3TokenCopy(&pStr1->token, &pRight->token);
|
|
pStr1->token.n = nPattern;
|
|
}
|
|
pStr2 = sqlite3ExprDup(pStr1);
|
|
if( pStr2 ){
|
|
assert( pStr2->token.dyn );
|
|
++*(u8*)&pStr2->token.z[nPattern-1];
|
|
}
|
|
pNewExpr1 = sqlite3Expr(TK_GE, sqlite3ExprDup(pLeft), pStr1, 0);
|
|
idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
exprAnalyze(pSrc, pMaskSet, pWC, idxNew1);
|
|
pNewExpr2 = sqlite3Expr(TK_LT, sqlite3ExprDup(pLeft), pStr2, 0);
|
|
idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC);
|
|
exprAnalyze(pSrc, pMaskSet, 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 */
|
|
}
|
|
|
|
|
|
/*
|
|
** 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 */
|
|
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.
|
|
*/
|
|
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 */
|
|
|
|
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 */
|
|
return 0;
|
|
}
|
|
pColl = sqlite3ExprCollSeq(pParse, pExpr);
|
|
if( !pColl ) pColl = db->pDfltColl;
|
|
if( pExpr->iColumn!=pIdx->aiColumn[i] ||
|
|
sqlite3StrICmp(pColl->zName, pIdx->azColl[i]) ){
|
|
/* 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 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( pIdx->aSortOrder[i]==0 || pIdx->aSortOrder[i]==1 );
|
|
termSortOrder = pIdx->aSortOrder[i] ^ 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++;
|
|
}
|
|
|
|
/* The index can be used for sorting if all terms of the ORDER BY clause
|
|
** are covered.
|
|
*/
|
|
if( j>=nTerm ){
|
|
*pbRev = sortOrder!=0;
|
|
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 */
|
|
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( pOrderBy->nExpr==1 && p->op==TK_COLUMN && p->iTable==base
|
|
&& p->iColumn==-1 ){
|
|
*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 operatings 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;
|
|
}
|
|
|
|
/*
|
|
** Find the best index for accessing a particular table. Return a pointer
|
|
** to the index, flags that describe how the index should be used, the
|
|
** number of equality constraints, and the "cost" for this index.
|
|
**
|
|
** The lowest cost index wins. The cost is an estimate of the amount of
|
|
** CPU and disk I/O need to process the request using the selected index.
|
|
** 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.
|
|
**
|
|
*/
|
|
static double 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 */
|
|
Index **ppIndex, /* Make *ppIndex point to the best index */
|
|
int *pFlags, /* Put flags describing this choice in *pFlags */
|
|
int *pnEq /* Put the number of == or IN constraints here */
|
|
){
|
|
WhereTerm *pTerm;
|
|
Index *bestIdx = 0; /* Index that gives the lowest cost */
|
|
double lowestCost; /* The cost of using bestIdx */
|
|
int bestFlags = 0; /* Flags associated with bestIdx */
|
|
int bestNEq = 0; /* Best value for nEq */
|
|
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 flags; /* Flags associated with pProbe */
|
|
int nEq; /* Number of == or IN constraints */
|
|
double cost; /* Cost of using pProbe */
|
|
|
|
TRACE(("bestIndex: tbl=%s notReady=%x\n", pSrc->pTab->zName, notReady));
|
|
lowestCost = SQLITE_BIG_DBL;
|
|
pProbe = pSrc->pTab->pIndex;
|
|
|
|
/* 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.
|
|
*/
|
|
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, &rev)) ){
|
|
*pFlags = 0;
|
|
*ppIndex = 0;
|
|
*pnEq = 0;
|
|
return 0.0;
|
|
}
|
|
|
|
/* Check for a rowid=EXPR or rowid IN (...) constraints
|
|
*/
|
|
pTerm = findTerm(pWC, iCur, -1, notReady, WO_EQ|WO_IN, 0);
|
|
if( pTerm ){
|
|
Expr *pExpr;
|
|
*ppIndex = 0;
|
|
bestFlags = 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 */
|
|
*pFlags = WHERE_ROWID_EQ | WHERE_UNIQUE;
|
|
*pnEq = 1;
|
|
TRACE(("... best is rowid\n"));
|
|
return 0.0;
|
|
}else if( (pExpr = pTerm->pExpr)->pList!=0 ){
|
|
/* Rowid IN (LIST): cost is NlogN where N is the number of list
|
|
** elements. */
|
|
lowestCost = pExpr->pList->nExpr;
|
|
lowestCost *= estLog(lowestCost);
|
|
}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. */
|
|
lowestCost = 200;
|
|
}
|
|
TRACE(("... rowid IN cost: %.9g\n", lowestCost));
|
|
}
|
|
|
|
/* 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;
|
|
TRACE(("... table scan base cost: %.9g\n", cost));
|
|
flags = 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) ){
|
|
flags |= WHERE_TOP_LIMIT;
|
|
cost /= 3; /* Guess that rowid<EXPR eliminates two-thirds or rows */
|
|
}
|
|
if( findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0) ){
|
|
flags |= WHERE_BTM_LIMIT;
|
|
cost /= 3; /* Guess that rowid>EXPR eliminates two-thirds of rows */
|
|
}
|
|
TRACE(("... rowid range reduces cost to %.9g\n", cost));
|
|
}else{
|
|
flags = 0;
|
|
}
|
|
|
|
/* 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, &rev) ){
|
|
flags |= WHERE_ORDERBY|WHERE_ROWID_RANGE;
|
|
if( rev ){
|
|
flags |= WHERE_REVERSE;
|
|
}
|
|
}else{
|
|
cost += cost*estLog(cost);
|
|
TRACE(("... sorting increases cost to %.9g\n", cost));
|
|
}
|
|
}
|
|
if( cost<lowestCost ){
|
|
lowestCost = cost;
|
|
bestFlags = flags;
|
|
}
|
|
|
|
/* Look at each index.
|
|
*/
|
|
for(; pProbe; pProbe=pProbe->pNext){
|
|
int i; /* Loop counter */
|
|
double inMultiplier = 1;
|
|
|
|
TRACE(("... index %s:\n", pProbe->zName));
|
|
|
|
/* Count the number of columns in the index that are satisfied
|
|
** by x=EXPR constraints or x IN (...) constraints.
|
|
*/
|
|
flags = 0;
|
|
for(i=0; i<pProbe->nColumn; i++){
|
|
int j = pProbe->aiColumn[i];
|
|
pTerm = findTerm(pWC, iCur, j, notReady, WO_EQ|WO_IN, pProbe);
|
|
if( pTerm==0 ) break;
|
|
flags |= WHERE_COLUMN_EQ;
|
|
if( pTerm->eOperator & WO_IN ){
|
|
Expr *pExpr = pTerm->pExpr;
|
|
flags |= WHERE_COLUMN_IN;
|
|
if( pExpr->pSelect!=0 ){
|
|
inMultiplier *= 100;
|
|
}else if( pExpr->pList!=0 ){
|
|
inMultiplier *= pExpr->pList->nExpr + 1;
|
|
}
|
|
}
|
|
}
|
|
cost = pProbe->aiRowEst[i] * inMultiplier * estLog(inMultiplier);
|
|
nEq = i;
|
|
if( pProbe->onError!=OE_None && (flags & WHERE_COLUMN_IN)==0
|
|
&& nEq==pProbe->nColumn ){
|
|
flags |= WHERE_UNIQUE;
|
|
}
|
|
TRACE(("...... nEq=%d inMult=%.9g cost=%.9g\n", nEq, inMultiplier, cost));
|
|
|
|
/* Look for range constraints
|
|
*/
|
|
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 ){
|
|
flags |= WHERE_COLUMN_RANGE;
|
|
if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pProbe) ){
|
|
flags |= WHERE_TOP_LIMIT;
|
|
cost /= 3;
|
|
}
|
|
if( findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pProbe) ){
|
|
flags |= WHERE_BTM_LIMIT;
|
|
cost /= 3;
|
|
}
|
|
TRACE(("...... range reduces cost to %.9g\n", cost));
|
|
}
|
|
}
|
|
|
|
/* Add the additional cost of sorting if that is a factor.
|
|
*/
|
|
if( pOrderBy ){
|
|
if( (flags & WHERE_COLUMN_IN)==0 &&
|
|
isSortingIndex(pParse,pProbe,iCur,pOrderBy,nEq,&rev) ){
|
|
if( flags==0 ){
|
|
flags = WHERE_COLUMN_RANGE;
|
|
}
|
|
flags |= WHERE_ORDERBY;
|
|
if( rev ){
|
|
flags |= WHERE_REVERSE;
|
|
}
|
|
}else{
|
|
cost += cost*estLog(cost);
|
|
TRACE(("...... orderby increases cost to %.9g\n", cost));
|
|
}
|
|
}
|
|
|
|
/* 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( flags && 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 ){
|
|
flags |= WHERE_IDX_ONLY;
|
|
cost /= 2;
|
|
TRACE(("...... idx-only reduces cost to %.9g\n", cost));
|
|
}
|
|
}
|
|
|
|
/* If this index has achieved the lowest cost so far, then use it.
|
|
*/
|
|
if( cost < lowestCost ){
|
|
bestIdx = pProbe;
|
|
lowestCost = cost;
|
|
assert( flags!=0 );
|
|
bestFlags = flags;
|
|
bestNEq = nEq;
|
|
}
|
|
}
|
|
|
|
/* Report the best result
|
|
*/
|
|
*ppIndex = bestIdx;
|
|
TRACE(("best index is %s, cost=%.9g, flags=%x, nEq=%d\n",
|
|
bestIdx ? bestIdx->zName : "(none)", lowestCost, bestFlags, bestNEq));
|
|
*pFlags = bestFlags;
|
|
*pnEq = bestNEq;
|
|
return lowestCost;
|
|
}
|
|
|
|
|
|
/*
|
|
** 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
|
|
&& (pTerm->flags & TERM_CODED)==0
|
|
&& (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
|
|
){
|
|
pTerm->flags |= TERM_CODED;
|
|
if( pTerm->iParent>=0 ){
|
|
WhereTerm *pOther = &pTerm->pWC->a[pTerm->iParent];
|
|
if( (--pOther->nChild)==0 ){
|
|
disableTerm(pLevel, pOther);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Generate code that builds a probe for an index. Details:
|
|
**
|
|
** * Check the top nColumn entries on the stack. If any
|
|
** of those entries are NULL, jump immediately to brk,
|
|
** which is the loop exit, since no index entry will match
|
|
** if any part of the key is NULL. Pop (nColumn+nExtra)
|
|
** elements from the stack.
|
|
**
|
|
** * Construct a probe entry from the top nColumn entries in
|
|
** the stack with affinities appropriate for index pIdx.
|
|
** Only nColumn elements are popped from the stack in this case
|
|
** (by OP_MakeRecord).
|
|
**
|
|
*/
|
|
static void buildIndexProbe(
|
|
Vdbe *v,
|
|
int nColumn,
|
|
int nExtra,
|
|
int brk,
|
|
Index *pIdx
|
|
){
|
|
sqlite3VdbeAddOp(v, OP_NotNull, -nColumn, sqlite3VdbeCurrentAddr(v)+3);
|
|
sqlite3VdbeAddOp(v, OP_Pop, nColumn+nExtra, 0);
|
|
sqlite3VdbeAddOp(v, OP_Goto, 0, brk);
|
|
sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
|
|
sqlite3IndexAffinityStr(v, pIdx);
|
|
}
|
|
|
|
|
|
/*
|
|
** 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 on the top of the stack.
|
|
**
|
|
** 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 void codeEqualityTerm(
|
|
Parse *pParse, /* The parsing context */
|
|
WhereTerm *pTerm, /* The term of the WHERE clause to be coded */
|
|
int brk, /* Jump here to abandon the loop */
|
|
WhereLevel *pLevel /* When level of the FROM clause we are working on */
|
|
){
|
|
Expr *pX = pTerm->pExpr;
|
|
if( pX->op!=TK_IN ){
|
|
assert( pX->op==TK_EQ );
|
|
sqlite3ExprCode(pParse, pX->pRight);
|
|
#ifndef SQLITE_OMIT_SUBQUERY
|
|
}else{
|
|
int iTab;
|
|
int *aIn;
|
|
Vdbe *v = pParse->pVdbe;
|
|
|
|
sqlite3CodeSubselect(pParse, pX);
|
|
iTab = pX->iTable;
|
|
sqlite3VdbeAddOp(v, OP_Rewind, iTab, brk);
|
|
VdbeComment((v, "# %.*s", pX->span.n, pX->span.z));
|
|
pLevel->nIn++;
|
|
sqliteReallocOrFree((void**)&pLevel->aInLoop,
|
|
sizeof(pLevel->aInLoop[0])*3*pLevel->nIn);
|
|
aIn = pLevel->aInLoop;
|
|
if( aIn ){
|
|
aIn += pLevel->nIn*3 - 3;
|
|
aIn[0] = OP_Next;
|
|
aIn[1] = iTab;
|
|
aIn[2] = sqlite3VdbeAddOp(v, OP_Column, iTab, 0);
|
|
}else{
|
|
pLevel->nIn = 0;
|
|
}
|
|
#endif
|
|
}
|
|
disableTerm(pLevel, pTerm);
|
|
}
|
|
|
|
/*
|
|
** 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 left
|
|
** on the stack - a is the deepest and b the shallowest.
|
|
**
|
|
** 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 puts
|
|
** the address of that memory cell in pLevel->iMem. The code that
|
|
** calls this routine will use pLevel->iMem 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 void 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 brk /* Jump here to end the loop */
|
|
){
|
|
int nEq = pLevel->nEq; /* The number of == or IN constraints to code */
|
|
int termsInMem = 0; /* If true, store value in mem[] cells */
|
|
Vdbe *v = pParse->pVdbe; /* The virtual machine under construction */
|
|
Index *pIdx = pLevel->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 */
|
|
|
|
/* Figure out how many memory cells we will need then allocate them.
|
|
** We always need at least one used to store the loop terminator
|
|
** value. If there are IN operators we'll need one for each == or
|
|
** IN constraint.
|
|
*/
|
|
pLevel->iMem = pParse->nMem++;
|
|
if( pLevel->flags & WHERE_COLUMN_IN ){
|
|
pParse->nMem += pLevel->nEq;
|
|
termsInMem = 1;
|
|
}
|
|
|
|
/* Evaluate the equality constraints
|
|
*/
|
|
for(j=0; j<pIdx->nColumn; j++){
|
|
int k = pIdx->aiColumn[j];
|
|
pTerm = findTerm(pWC, iCur, k, notReady, WO_EQ|WO_IN, pIdx);
|
|
if( pTerm==0 ) break;
|
|
assert( (pTerm->flags & TERM_CODED)==0 );
|
|
codeEqualityTerm(pParse, pTerm, brk, pLevel);
|
|
if( termsInMem ){
|
|
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem+j+1, 1);
|
|
}
|
|
}
|
|
assert( j==nEq );
|
|
|
|
/* Make sure all the constraint values are on the top of the stack
|
|
*/
|
|
if( termsInMem ){
|
|
for(j=0; j<nEq; j++){
|
|
sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem+j+1, 0);
|
|
}
|
|
}
|
|
}
|
|
|
|
#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 */
|
|
|
|
|
|
|
|
/*
|
|
** 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 */
|
|
){
|
|
int i; /* Loop counter */
|
|
WhereInfo *pWInfo; /* Will become the return value of this function */
|
|
Vdbe *v = pParse->pVdbe; /* The virtual database engine */
|
|
int brk, cont = 0; /* Addresses used during code generation */
|
|
Bitmask notReady; /* Cursors that are not yet positioned */
|
|
WhereTerm *pTerm; /* A single term in the WHERE clause */
|
|
ExprMaskSet maskSet; /* The expression mask set */
|
|
WhereClause wc; /* The WHERE clause is divided into these terms */
|
|
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 wc.a[].flags */
|
|
|
|
/* 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;
|
|
}
|
|
|
|
/* Split the WHERE clause into separate subexpressions where each
|
|
** subexpression is separated by an AND operator.
|
|
*/
|
|
initMaskSet(&maskSet);
|
|
whereClauseInit(&wc, pParse);
|
|
whereSplit(&wc, pWhere, TK_AND);
|
|
|
|
/* Allocate and initialize the WhereInfo structure that will become the
|
|
** return value.
|
|
*/
|
|
pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel));
|
|
if( sqlite3MallocFailed() ){
|
|
goto whereBeginNoMem;
|
|
}
|
|
pWInfo->pParse = pParse;
|
|
pWInfo->pTabList = pTabList;
|
|
pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
|
|
|
|
/* 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 || sqlite3ExprIsConstant(pWhere)) ){
|
|
sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1);
|
|
pWhere = 0;
|
|
}
|
|
|
|
/* 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.
|
|
*/
|
|
for(i=0; i<pTabList->nSrc; i++){
|
|
createMask(&maskSet, pTabList->a[i].iCursor);
|
|
}
|
|
exprAnalyzeAll(pTabList, &maskSet, &wc);
|
|
if( sqlite3MallocFailed() ){
|
|
goto whereBeginNoMem;
|
|
}
|
|
|
|
/* 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[].flags WHERE_xxx flags associated with pIdx
|
|
** pWInfo->a[].nEq The number of == and IN constraints
|
|
** pWInfo->a[].iFrom When 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
|
|
**
|
|
** 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;
|
|
TRACE(("*** Optimizer Start ***\n"));
|
|
for(i=iFrom=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
|
|
Index *pIdx; /* Index for FROM table at pTabItem */
|
|
int flags; /* Flags asssociated with pIdx */
|
|
int nEq; /* Number of == or IN constraints */
|
|
double cost; /* The cost for pIdx */
|
|
int j; /* For looping over FROM tables */
|
|
Index *pBest = 0; /* The best index seen so far */
|
|
int bestFlags = 0; /* Flags associated with pBest */
|
|
int bestNEq = 0; /* nEq associated with pBest */
|
|
double lowestCost; /* Cost of the pBest */
|
|
int bestJ = 0; /* The value of j */
|
|
Bitmask m; /* Bitmask value for j or bestJ */
|
|
int once = 0; /* True when first table is seen */
|
|
|
|
lowestCost = SQLITE_BIG_DBL;
|
|
for(j=iFrom, pTabItem=&pTabList->a[j]; j<pTabList->nSrc; j++, pTabItem++){
|
|
if( once &&
|
|
((pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0
|
|
|| (j>0 && (pTabItem[-1].jointype & (JT_LEFT|JT_CROSS))!=0))
|
|
){
|
|
break;
|
|
}
|
|
m = getMask(&maskSet, pTabItem->iCursor);
|
|
if( (m & notReady)==0 ){
|
|
if( j==iFrom ) iFrom++;
|
|
continue;
|
|
}
|
|
cost = bestIndex(pParse, &wc, pTabItem, notReady,
|
|
(i==0 && ppOrderBy) ? *ppOrderBy : 0,
|
|
&pIdx, &flags, &nEq);
|
|
if( cost<lowestCost ){
|
|
once = 1;
|
|
lowestCost = cost;
|
|
pBest = pIdx;
|
|
bestFlags = flags;
|
|
bestNEq = nEq;
|
|
bestJ = j;
|
|
}
|
|
}
|
|
TRACE(("*** Optimizer choose table %d for loop %d\n", bestJ,
|
|
pLevel-pWInfo->a));
|
|
if( (bestFlags & WHERE_ORDERBY)!=0 ){
|
|
*ppOrderBy = 0;
|
|
}
|
|
andFlags &= bestFlags;
|
|
pLevel->flags = bestFlags;
|
|
pLevel->pIdx = pBest;
|
|
pLevel->nEq = bestNEq;
|
|
pLevel->aInLoop = 0;
|
|
pLevel->nIn = 0;
|
|
if( pBest ){
|
|
pLevel->iIdxCur = pParse->nTab++;
|
|
}else{
|
|
pLevel->iIdxCur = -1;
|
|
}
|
|
notReady &= ~getMask(&maskSet, pTabList->a[bestJ].iCursor);
|
|
pLevel->iFrom = bestJ;
|
|
}
|
|
TRACE(("*** Optimizer Finished ***\n"));
|
|
|
|
/* If the total query only selects a single row, then the ORDER BY
|
|
** clause is irrelevant.
|
|
*/
|
|
if( (andFlags & WHERE_UNIQUE)!=0 && ppOrderBy ){
|
|
*ppOrderBy = 0;
|
|
}
|
|
|
|
/* Open all tables in the pTabList and any indices selected for
|
|
** searching those tables.
|
|
*/
|
|
sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
|
|
pLevel = pWInfo->a;
|
|
for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
|
|
Table *pTab; /* Table to open */
|
|
Index *pIx; /* Index used to access pTab (if any) */
|
|
int iDb; /* Index of database containing table/index */
|
|
int iIdxCur = pLevel->iIdxCur;
|
|
|
|
#ifndef SQLITE_OMIT_EXPLAIN
|
|
if( pParse->explain==2 ){
|
|
char *zMsg;
|
|
struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
|
|
zMsg = sqlite3MPrintf("TABLE %s", pItem->zName);
|
|
if( pItem->zAlias ){
|
|
zMsg = sqlite3MPrintf("%z AS %s", zMsg, pItem->zAlias);
|
|
}
|
|
if( (pIx = pLevel->pIdx)!=0 ){
|
|
zMsg = sqlite3MPrintf("%z WITH INDEX %s", zMsg, pIx->zName);
|
|
}else if( pLevel->flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
|
|
zMsg = sqlite3MPrintf("%z USING PRIMARY KEY", zMsg);
|
|
}
|
|
sqlite3VdbeOp3(v, OP_Explain, i, pLevel->iFrom, zMsg, P3_DYNAMIC);
|
|
}
|
|
#endif /* SQLITE_OMIT_EXPLAIN */
|
|
pTabItem = &pTabList->a[pLevel->iFrom];
|
|
pTab = pTabItem->pTab;
|
|
iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
|
|
if( pTab->isTransient || pTab->pSelect ) continue;
|
|
if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){
|
|
sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, OP_OpenRead);
|
|
if( pTab->nCol<(sizeof(Bitmask)*8) ){
|
|
Bitmask b = pTabItem->colUsed;
|
|
int n = 0;
|
|
for(; b; b=b>>1, n++){}
|
|
sqlite3VdbeChangeP2(v, sqlite3VdbeCurrentAddr(v)-1, n);
|
|
assert( n<=pTab->nCol );
|
|
}
|
|
}else{
|
|
sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
|
|
}
|
|
pLevel->iTabCur = pTabItem->iCursor;
|
|
if( (pIx = pLevel->pIdx)!=0 ){
|
|
KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx);
|
|
assert( pIx->pSchema==pTab->pSchema );
|
|
sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
|
|
VdbeComment((v, "# %s", pIx->zName));
|
|
sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum,
|
|
(char*)pKey, P3_KEYINFO_HANDOFF);
|
|
}
|
|
if( (pLevel->flags & WHERE_IDX_ONLY)!=0 ){
|
|
sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, pIx->nColumn+1);
|
|
}
|
|
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, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
|
|
int j;
|
|
int iCur = pTabItem->iCursor; /* The VDBE cursor for the table */
|
|
Index *pIdx; /* The index we will be using */
|
|
int iIdxCur; /* The VDBE cursor for the index */
|
|
int omitTable; /* True if we use the index only */
|
|
int bRev; /* True if we need to scan in reverse order */
|
|
|
|
pTabItem = &pTabList->a[pLevel->iFrom];
|
|
iCur = pTabItem->iCursor;
|
|
pIdx = pLevel->pIdx;
|
|
iIdxCur = pLevel->iIdxCur;
|
|
bRev = (pLevel->flags & WHERE_REVERSE)!=0;
|
|
omitTable = (pLevel->flags & WHERE_IDX_ONLY)!=0;
|
|
|
|
/* Create labels for the "break" and "continue" instructions
|
|
** for the current loop. Jump to brk to break out of a loop.
|
|
** Jump to cont to go immediately to the next iteration of the
|
|
** loop.
|
|
*/
|
|
brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
|
|
cont = pLevel->cont = 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[-1].jointype & JT_LEFT)!=0 ){
|
|
if( !pParse->nMem ) pParse->nMem++;
|
|
pLevel->iLeftJoin = pParse->nMem++;
|
|
sqlite3VdbeAddOp(v, OP_MemInt, 0, pLevel->iLeftJoin);
|
|
VdbeComment((v, "# init LEFT JOIN no-match flag"));
|
|
}
|
|
|
|
if( pLevel->flags & 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.
|
|
*/
|
|
pTerm = findTerm(&wc, iCur, -1, notReady, WO_EQ|WO_IN, 0);
|
|
assert( pTerm!=0 );
|
|
assert( pTerm->pExpr!=0 );
|
|
assert( pTerm->leftCursor==iCur );
|
|
assert( omitTable==0 );
|
|
codeEqualityTerm(pParse, pTerm, brk, pLevel);
|
|
sqlite3VdbeAddOp(v, OP_MustBeInt, 1, brk);
|
|
sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk);
|
|
VdbeComment((v, "pk"));
|
|
pLevel->op = OP_Noop;
|
|
}else if( pLevel->flags & WHERE_ROWID_RANGE ){
|
|
/* Case 2: We have an inequality comparison against the ROWID field.
|
|
*/
|
|
int testOp = OP_Noop;
|
|
int start;
|
|
WhereTerm *pStart, *pEnd;
|
|
|
|
assert( omitTable==0 );
|
|
pStart = findTerm(&wc, iCur, -1, notReady, WO_GT|WO_GE, 0);
|
|
pEnd = findTerm(&wc, iCur, -1, notReady, WO_LT|WO_LE, 0);
|
|
if( bRev ){
|
|
pTerm = pStart;
|
|
pStart = pEnd;
|
|
pEnd = pTerm;
|
|
}
|
|
if( pStart ){
|
|
Expr *pX;
|
|
pX = pStart->pExpr;
|
|
assert( pX!=0 );
|
|
assert( pStart->leftCursor==iCur );
|
|
sqlite3ExprCode(pParse, pX->pRight);
|
|
sqlite3VdbeAddOp(v, OP_ForceInt, pX->op==TK_LE || pX->op==TK_GT, brk);
|
|
sqlite3VdbeAddOp(v, bRev ? OP_MoveLt : OP_MoveGe, iCur, brk);
|
|
VdbeComment((v, "pk"));
|
|
disableTerm(pLevel, pStart);
|
|
}else{
|
|
sqlite3VdbeAddOp(v, bRev ? OP_Last : OP_Rewind, iCur, brk);
|
|
}
|
|
if( pEnd ){
|
|
Expr *pX;
|
|
pX = pEnd->pExpr;
|
|
assert( pX!=0 );
|
|
assert( pEnd->leftCursor==iCur );
|
|
sqlite3ExprCode(pParse, pX->pRight);
|
|
pLevel->iMem = pParse->nMem++;
|
|
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
|
|
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;
|
|
if( testOp!=OP_Noop ){
|
|
sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
|
|
sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
|
|
sqlite3VdbeAddOp(v, testOp, SQLITE_AFF_NUMERIC, brk);
|
|
}
|
|
}else if( pLevel->flags & WHERE_COLUMN_RANGE ){
|
|
/* Case 3: The WHERE clause term that refers to the right-most
|
|
** column of the index is an inequality. For example, if
|
|
** the index is on (x,y,z) and the WHERE clause is of the
|
|
** form "x=5 AND y<10" then this case is used. Only the
|
|
** right-most column can be an inequality - the rest must
|
|
** use the "==" and "IN" operators.
|
|
**
|
|
** 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 start;
|
|
int nEq = pLevel->nEq;
|
|
int topEq=0; /* True if top limit uses ==. False is strictly < */
|
|
int btmEq=0; /* True if btm limit uses ==. False if strictly > */
|
|
int topOp, btmOp; /* Operators for the top and bottom search bounds */
|
|
int testOp;
|
|
int nNotNull; /* Number of rows of index that must be non-NULL */
|
|
int topLimit = (pLevel->flags & WHERE_TOP_LIMIT)!=0;
|
|
int btmLimit = (pLevel->flags & WHERE_BTM_LIMIT)!=0;
|
|
|
|
/* Generate code to evaluate all constraint terms using == or IN
|
|
** and level the values of those terms on the stack.
|
|
*/
|
|
codeAllEqualityTerms(pParse, pLevel, &wc, notReady, brk);
|
|
|
|
/* Duplicate the equality term values because they will all be
|
|
** used twice: once to make the termination key and once to make the
|
|
** start key.
|
|
*/
|
|
for(j=0; j<nEq; j++){
|
|
sqlite3VdbeAddOp(v, OP_Dup, nEq-1, 0);
|
|
}
|
|
|
|
/* Figure out what comparison operators to use for top and bottom
|
|
** search bounds. For an ascending index, the bottom bound is a > or >=
|
|
** operator and the top bound is a < or <= operator. For a descending
|
|
** index the operators are reversed.
|
|
*/
|
|
nNotNull = nEq + topLimit;
|
|
if( pIdx->aSortOrder[nEq]==SQLITE_SO_ASC ){
|
|
topOp = WO_LT|WO_LE;
|
|
btmOp = WO_GT|WO_GE;
|
|
}else{
|
|
topOp = WO_GT|WO_GE;
|
|
btmOp = WO_LT|WO_LE;
|
|
SWAP(int, topLimit, btmLimit);
|
|
}
|
|
|
|
/* Generate the termination key. This is the key value that
|
|
** will end the search. There is no termination key if there
|
|
** are no equality terms and no "X<..." term.
|
|
**
|
|
** 2002-Dec-04: On a reverse-order scan, the so-called "termination"
|
|
** key computed here really ends up being the start key.
|
|
*/
|
|
if( topLimit ){
|
|
Expr *pX;
|
|
int k = pIdx->aiColumn[j];
|
|
pTerm = findTerm(&wc, iCur, k, notReady, topOp, pIdx);
|
|
assert( pTerm!=0 );
|
|
pX = pTerm->pExpr;
|
|
assert( (pTerm->flags & TERM_CODED)==0 );
|
|
sqlite3ExprCode(pParse, pX->pRight);
|
|
topEq = pTerm->eOperator & (WO_LE|WO_GE);
|
|
disableTerm(pLevel, pTerm);
|
|
testOp = OP_IdxGE;
|
|
}else{
|
|
testOp = nEq>0 ? OP_IdxGE : OP_Noop;
|
|
topEq = 1;
|
|
}
|
|
if( testOp!=OP_Noop ){
|
|
int nCol = nEq + topLimit;
|
|
pLevel->iMem = pParse->nMem++;
|
|
buildIndexProbe(v, nCol, nEq, brk, pIdx);
|
|
if( bRev ){
|
|
int op = topEq ? OP_MoveLe : OP_MoveLt;
|
|
sqlite3VdbeAddOp(v, op, iIdxCur, brk);
|
|
}else{
|
|
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
|
|
}
|
|
}else if( bRev ){
|
|
sqlite3VdbeAddOp(v, OP_Last, iIdxCur, brk);
|
|
}
|
|
|
|
/* Generate the start key. This is the key that defines the lower
|
|
** bound on the search. There is no start key if there are no
|
|
** equality terms and if there is no "X>..." term. In
|
|
** that case, generate a "Rewind" instruction in place of the
|
|
** start key search.
|
|
**
|
|
** 2002-Dec-04: In the case of a reverse-order search, the so-called
|
|
** "start" key really ends up being used as the termination key.
|
|
*/
|
|
if( btmLimit ){
|
|
Expr *pX;
|
|
int k = pIdx->aiColumn[j];
|
|
pTerm = findTerm(&wc, iCur, k, notReady, btmOp, pIdx);
|
|
assert( pTerm!=0 );
|
|
pX = pTerm->pExpr;
|
|
assert( (pTerm->flags & TERM_CODED)==0 );
|
|
sqlite3ExprCode(pParse, pX->pRight);
|
|
btmEq = pTerm->eOperator & (WO_LE|WO_GE);
|
|
disableTerm(pLevel, pTerm);
|
|
}else{
|
|
btmEq = 1;
|
|
}
|
|
if( nEq>0 || btmLimit ){
|
|
int nCol = nEq + btmLimit;
|
|
buildIndexProbe(v, nCol, 0, brk, pIdx);
|
|
if( bRev ){
|
|
pLevel->iMem = pParse->nMem++;
|
|
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
|
|
testOp = OP_IdxLT;
|
|
}else{
|
|
int op = btmEq ? OP_MoveGe : OP_MoveGt;
|
|
sqlite3VdbeAddOp(v, op, iIdxCur, brk);
|
|
}
|
|
}else if( bRev ){
|
|
testOp = OP_Noop;
|
|
}else{
|
|
sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, brk);
|
|
}
|
|
|
|
/* Generate the the top of the loop. If there is a termination
|
|
** key we have to test for that key and abort at the top of the
|
|
** loop.
|
|
*/
|
|
start = sqlite3VdbeCurrentAddr(v);
|
|
if( testOp!=OP_Noop ){
|
|
sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
|
|
sqlite3VdbeAddOp(v, testOp, iIdxCur, brk);
|
|
if( (topEq && !bRev) || (!btmEq && bRev) ){
|
|
sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC);
|
|
}
|
|
}
|
|
sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0);
|
|
sqlite3VdbeAddOp(v, OP_IdxIsNull, nNotNull, cont);
|
|
if( !omitTable ){
|
|
sqlite3VdbeAddOp(v, OP_IdxRowid, iIdxCur, 0);
|
|
sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
|
|
}
|
|
|
|
/* Record the instruction used to terminate the loop.
|
|
*/
|
|
pLevel->op = bRev ? OP_Prev : OP_Next;
|
|
pLevel->p1 = iIdxCur;
|
|
pLevel->p2 = start;
|
|
}else if( pLevel->flags & WHERE_COLUMN_EQ ){
|
|
/* Case 4: There is an index and all terms of the WHERE clause that
|
|
** refer to the index using the "==" or "IN" operators.
|
|
*/
|
|
int start;
|
|
int nEq = pLevel->nEq;
|
|
|
|
/* Generate code to evaluate all constraint terms using == or IN
|
|
** and leave the values of those terms on the stack.
|
|
*/
|
|
codeAllEqualityTerms(pParse, pLevel, &wc, notReady, brk);
|
|
|
|
/* Generate a single key that will be used to both start and terminate
|
|
** the search
|
|
*/
|
|
buildIndexProbe(v, nEq, 0, brk, pIdx);
|
|
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 0);
|
|
|
|
/* Generate code (1) to move to the first matching element of the table.
|
|
** Then generate code (2) that jumps to "brk" after the cursor is past
|
|
** the last matching element of the table. The code (1) is executed
|
|
** once to initialize the search, the code (2) is executed before each
|
|
** iteration of the scan to see if the scan has finished. */
|
|
if( bRev ){
|
|
/* Scan in reverse order */
|
|
sqlite3VdbeAddOp(v, OP_MoveLe, iIdxCur, brk);
|
|
start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
|
|
sqlite3VdbeAddOp(v, OP_IdxLT, iIdxCur, brk);
|
|
pLevel->op = OP_Prev;
|
|
}else{
|
|
/* Scan in the forward order */
|
|
sqlite3VdbeAddOp(v, OP_MoveGe, iIdxCur, brk);
|
|
start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
|
|
sqlite3VdbeOp3(v, OP_IdxGE, iIdxCur, brk, "+", P3_STATIC);
|
|
pLevel->op = OP_Next;
|
|
}
|
|
sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0);
|
|
sqlite3VdbeAddOp(v, OP_IdxIsNull, nEq, cont);
|
|
if( !omitTable ){
|
|
sqlite3VdbeAddOp(v, OP_IdxRowid, iIdxCur, 0);
|
|
sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
|
|
}
|
|
pLevel->p1 = iIdxCur;
|
|
pLevel->p2 = start;
|
|
}else{
|
|
/* Case 5: There is no usable index. We must do a complete
|
|
** scan of the entire table.
|
|
*/
|
|
assert( omitTable==0 );
|
|
assert( bRev==0 );
|
|
pLevel->op = OP_Next;
|
|
pLevel->p1 = iCur;
|
|
pLevel->p2 = 1 + sqlite3VdbeAddOp(v, OP_Rewind, iCur, brk);
|
|
}
|
|
notReady &= ~getMask(&maskSet, iCur);
|
|
|
|
/* Insert code to test every subexpression that can be completely
|
|
** computed using the current set of tables.
|
|
*/
|
|
for(pTerm=wc.a, j=wc.nTerm; j>0; j--, pTerm++){
|
|
Expr *pE;
|
|
if( pTerm->flags & (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, cont, 1);
|
|
pTerm->flags |= 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->top = sqlite3VdbeCurrentAddr(v);
|
|
sqlite3VdbeAddOp(v, OP_MemInt, 1, pLevel->iLeftJoin);
|
|
VdbeComment((v, "# record LEFT JOIN hit"));
|
|
for(pTerm=wc.a, j=0; j<wc.nTerm; j++, pTerm++){
|
|
if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue;
|
|
if( (pTerm->prereqAll & notReady)!=0 ) continue;
|
|
assert( pTerm->pExpr );
|
|
sqlite3ExprIfFalse(pParse, pTerm->pExpr, cont, 1);
|
|
pTerm->flags |= TERM_CODED;
|
|
}
|
|
}
|
|
}
|
|
|
|
#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 = strlen(z);
|
|
if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){
|
|
if( pLevel->flags & WHERE_IDX_ONLY ){
|
|
strcpy(&sqlite3_query_plan[nQPlan], "{}");
|
|
nQPlan += 2;
|
|
}else{
|
|
strcpy(&sqlite3_query_plan[nQPlan], z);
|
|
nQPlan += n;
|
|
}
|
|
sqlite3_query_plan[nQPlan++] = ' ';
|
|
}
|
|
if( pLevel->flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
|
|
strcpy(&sqlite3_query_plan[nQPlan], "* ");
|
|
nQPlan += 2;
|
|
}else if( pLevel->pIdx==0 ){
|
|
strcpy(&sqlite3_query_plan[nQPlan], "{} ");
|
|
nQPlan += 3;
|
|
}else{
|
|
n = strlen(pLevel->pIdx->zName);
|
|
if( n+nQPlan < sizeof(sqlite3_query_plan)-2 ){
|
|
strcpy(&sqlite3_query_plan[nQPlan], pLevel->pIdx->zName);
|
|
nQPlan += n;
|
|
sqlite3_query_plan[nQPlan++] = ' ';
|
|
}
|
|
}
|
|
}
|
|
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.
|
|
*/
|
|
pWInfo->iContinue = cont;
|
|
whereClauseClear(&wc);
|
|
return pWInfo;
|
|
|
|
/* Jump here if malloc fails */
|
|
whereBeginNoMem:
|
|
whereClauseClear(&wc);
|
|
sqliteFree(pWInfo);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
** Generate the end of the WHERE loop. See comments on
|
|
** sqlite3WhereBegin() for additional information.
|
|
*/
|
|
void sqlite3WhereEnd(WhereInfo *pWInfo){
|
|
Vdbe *v = pWInfo->pParse->pVdbe;
|
|
int i;
|
|
WhereLevel *pLevel;
|
|
SrcList *pTabList = pWInfo->pTabList;
|
|
|
|
/* Generate loop termination code.
|
|
*/
|
|
for(i=pTabList->nSrc-1; i>=0; i--){
|
|
pLevel = &pWInfo->a[i];
|
|
sqlite3VdbeResolveLabel(v, pLevel->cont);
|
|
if( pLevel->op!=OP_Noop ){
|
|
sqlite3VdbeAddOp(v, pLevel->op, pLevel->p1, pLevel->p2);
|
|
}
|
|
sqlite3VdbeResolveLabel(v, pLevel->brk);
|
|
if( pLevel->nIn ){
|
|
int *a;
|
|
int j;
|
|
for(j=pLevel->nIn, a=&pLevel->aInLoop[j*3-3]; j>0; j--, a-=3){
|
|
sqlite3VdbeAddOp(v, a[0], a[1], a[2]);
|
|
}
|
|
sqliteFree(pLevel->aInLoop);
|
|
}
|
|
if( pLevel->iLeftJoin ){
|
|
int addr;
|
|
addr = sqlite3VdbeAddOp(v, OP_IfMemPos, pLevel->iLeftJoin, 0);
|
|
sqlite3VdbeAddOp(v, OP_NullRow, pTabList->a[i].iCursor, 0);
|
|
if( pLevel->iIdxCur>=0 ){
|
|
sqlite3VdbeAddOp(v, OP_NullRow, pLevel->iIdxCur, 0);
|
|
}
|
|
sqlite3VdbeAddOp(v, OP_Goto, 0, pLevel->top);
|
|
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->isTransient || pTab->pSelect ) continue;
|
|
if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){
|
|
sqlite3VdbeAddOp(v, OP_Close, pTabItem->iCursor, 0);
|
|
}
|
|
if( pLevel->pIdx!=0 ){
|
|
sqlite3VdbeAddOp(v, OP_Close, pLevel->iIdxCur, 0);
|
|
}
|
|
|
|
/* Make cursor substitutions for cases where we want to use
|
|
** just the index and never reference the table.
|
|
**
|
|
** 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->flags & WHERE_IDX_ONLY ){
|
|
int k, j, last;
|
|
VdbeOp *pOp;
|
|
Index *pIdx = pLevel->pIdx;
|
|
|
|
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 ){
|
|
pOp->p1 = pLevel->iIdxCur;
|
|
for(j=0; j<pIdx->nColumn; j++){
|
|
if( pOp->p2==pIdx->aiColumn[j] ){
|
|
pOp->p2 = j;
|
|
break;
|
|
}
|
|
}
|
|
}else if( pOp->opcode==OP_Rowid ){
|
|
pOp->p1 = pLevel->iIdxCur;
|
|
pOp->opcode = OP_IdxRowid;
|
|
}else if( pOp->opcode==OP_NullRow ){
|
|
pOp->opcode = OP_Noop;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Final cleanup
|
|
*/
|
|
sqliteFree(pWInfo);
|
|
return;
|
|
}
|