** so is applicable. Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
-** $Id: where.c,v 1.147 2005/07/19 22:22:13 drh Exp $
+** $Id: where.c,v 1.148 2005/07/21 03:15:00 drh Exp $
*/
#include "sqliteInt.h"
*/
typedef struct WhereClause WhereClause;
+/*
+** An instance of the following structure holds information about how well
+** a particular index helps in a search. A list of such structures is
+** attached to each SrcList_item of a SrcList.
+*/
+struct WhereIdx {
+ Index *pIdx; /* The index under consideration */
+ Bitmask prereq; /* Prerequesite FROM clause elements for using this index */
+ int nEqTerm; /* Number of Idx column constrainted by == or IN */
+ int nTerm; /* Total number of Index Columns used */
+ int flags; /* Flags. See below */
+ double rRowEst; /* Estimated number of rows selected */
+ double rScore; /* Score of this index */
+ WhereIdx *pNext; /* Next WhereIdx on the same FROM clause element */
+};
+
/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause. Each WHERE
u16 flags; /* Bit flags. See below */
i16 leftCursor; /* Cursor number of X in "X <op> <expr>" */
i16 leftColumn; /* Column number of X in "X <op> <expr>" */
+ u8 operator; /* A WO_xx value describing <op> */
WhereClause *pWC; /* The clause this term is part of */
Bitmask prereqRight; /* Bitmask of tables used by pRight */
Bitmask prereqAll; /* Bitmask of tables referenced by p */
** WHERE clause. Mostly this is a container for one or more WhereTerms.
*/
struct WhereClause {
+ Parse *pParse; /* The parser context */
int nTerm; /* Number of terms */
int nSlot; /* Number of entries in a[] */
WhereTerm *a; /* Pointer to an array of terms */
/*
** Initialize a preallocated WhereClause structure.
*/
-static void whereClauseInit(WhereClause *pWC){
+static void whereClauseInit(WhereClause *pWC, Parse *pParse){
+ pWC->pParse = pParse;
pWC->nTerm = 0;
pWC->nSlot = ARRAYSIZE(pWC->aStatic);
pWC->a = pWC->aStatic;
** "=", "<", ">", "<=", ">=", and "IN".
*/
static int allowedOp(int op){
- assert( TK_GT==TK_LE-1 && TK_LE==TK_LT-1 && TK_LT==TK_GE-1 && TK_EQ==TK_GT-1);
+ assert( TK_GT>TK_EQ && TK_GT<TK_GE );
+ assert( TK_LT>TK_EQ && TK_LT<TK_GE );
+ assert( TK_LE>TK_EQ && TK_LE<TK_GE );
+ assert( TK_GE==TK_EQ+4 );
return op==TK_IN || (op>=TK_EQ && op<=TK_GE);
}
** are converted into "Y op X".
*/
static void exprCommute(Expr *pExpr){
- assert(
- pExpr->op==TK_EQ ||
- pExpr->op==TK_NE ||
- pExpr->op==TK_LT ||
- pExpr->op==TK_LE ||
- pExpr->op==TK_GT ||
- pExpr->op==TK_GE
- );
+ assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl);
SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
if( pExpr->op>=TK_GT ){
}
}
+/*
+** Bitmasks for the operators that indices are able to exploit. An
+** OR-ed combination of these values can be used when searching for
+** terms in the where clause.
+*/
+#define WO_IN 1
+#define WO_EQ 2
+#define WO_LT (2<<(TK_LT-TK_EQ))
+#define WO_LE (2<<(TK_LE-TK_EQ))
+#define WO_GT (2<<(TK_GT-TK_EQ))
+#define WO_GE (2<<(TK_GE-TK_EQ))
+
+/*
+** Translate from TK_xx operator to WO_xx bitmask.
+*/
+static int operatorMask(int op){
+ assert( allowedOp(op) );
+ if( op==TK_IN ){
+ return WO_IN;
+ }else{
+ return 1<<(op+1-TK_EQ);
+ }
+}
+
+/*
+** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
+** where X is a reference to the iColumn of table iCur and <op> is one of
+** the WO_xx operator codes specified by the op parameter.
+** Return a pointer to the term. Return 0 if not found.
+*/
+static WhereTerm *findTerm(
+ WhereClause *pWC, /* The WHERE clause to be searched */
+ int iCur, /* Cursor number of LHS */
+ int iColumn, /* Column number of LHS */
+ Bitmask notReady, /* RHS must not overlap with this mask */
+ u8 op, /* Mask of WO_xx values describing operator */
+ Index *pIdx /* Must be compatible with this index, if not NULL */
+){
+ WhereTerm *pTerm;
+ int k;
+ for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){
+ if( pTerm->leftCursor==iCur
+ && (pTerm->prereqRight & notReady)==0
+ && pTerm->leftColumn==iColumn
+ && (pTerm->operator & op)!=0
+ ){
+ if( iCur>=0 && pIdx ){
+ Expr *pX = pTerm->pExpr;
+ CollSeq *pColl;
+ char idxaff;
+ int k;
+ Parse *pParse = pWC->pParse;
+
+ idxaff = pIdx->pTable->aCol[iColumn].affinity;
+ if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue;
+ pColl = sqlite3ExprCollSeq(pParse, pX->pLeft);
+ if( !pColl ){
+ if( pX->pRight ){
+ pColl = sqlite3ExprCollSeq(pParse, pX->pRight);
+ }
+ if( !pColl ){
+ pColl = pParse->db->pDfltColl;
+ }
+ }
+ for(k=0; k<pIdx->nColumn && pIdx->aiColumn[k]!=iColumn; k++){}
+ assert( k<pIdx->nColumn );
+ if( pColl!=pIdx->keyInfo.aColl[k] ) continue;
+ }
+ return pTerm;
+ }
+ }
+ return 0;
+}
+
/*
** The input to this routine is an WhereTerm structure with only the
** "p" field filled in. The job of this routine is to analyze the
pTerm->prereqAll = prereqAll = exprTableUsage(pMaskSet, pExpr);
pTerm->leftCursor = -1;
pTerm->iPartner = -1;
+ pTerm->operator = 0;
idxRight = -1;
if( allowedOp(pExpr->op) && (pTerm->prereqRight & prereqLeft)==0 ){
Expr *pLeft = pExpr->pLeft;
if( pLeft->op==TK_COLUMN ){
pTerm->leftCursor = pLeft->iTable;
pTerm->leftColumn = pLeft->iColumn;
+ pTerm->operator = operatorMask(pExpr->op);
}
if( pRight && pRight->op==TK_COLUMN ){
WhereTerm *pNew;
pNew->leftColumn = pLeft->iColumn;
pNew->prereqRight = prereqLeft;
pNew->prereqAll = prereqAll;
+ pNew->operator = operatorMask(pDup->op);
}
}
}
return 0;
}
+/*
+** Value for flags returned by bestIndex()
+*/
+#define WHERE_ROWID_EQ 0x001 /* rowid=EXPR or rowid IN (...) */
+#define WHERE_ROWID_RANGE 0x002 /* rowid<EXPR and/or rowid>EXPR */
+#define WHERE_COLUMN_EQ 0x004 /* x=EXPR or x IN (...) */
+#define WHERE_COLUMN_RANGE 0x008 /* x<EXPR and/or x>EXPR */
+#define WHERE_SCAN 0x010 /* Do a full table scan */
+#define WHERE_REVERSE 0x020 /* Scan in reverse order */
+#define WHERE_ORDERBY 0x040 /* Output will appear in correct order */
+#define WHERE_IDX_ONLY 0x080 /* Use index only - omit table */
+#define WHERE_TOP_LIMIT 0x100 /* x<EXPR or x<=EXPR constraint */
+#define WHERE_BTM_LIMIT 0x200 /* x>EXPR or x>=EXPR constraint */
+
+/*
+** Find the best index for accessing a particular table. Return the index,
+** flags that describe how the index should be used, and the "score" for
+** this index.
+*/
+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 */
+){
+ WhereTerm *pTerm;
+ Index *pProbe;
+ Index *bestIdx = 0;
+ double bestScore = 0.0;
+ int bestFlags = 0;
+ int iCur = pSrc->iCursor;
+ int rev;
+
+ /* Check for a rowid=EXPR or rowid IN (...) constraint
+ */
+ pTerm = findTerm(pWC, iCur, -1, notReady, WO_EQ|WO_IN, 0);
+ if( pTerm ){
+ *ppIndex = 0;
+ if( pTerm->operator & WO_EQ ){
+ *pFlags = WHERE_ROWID_EQ;
+ if( pOrderBy ) *pFlags |= WHERE_ORDERBY;
+ return 1.0e10;
+ }else{
+ *pFlags = WHERE_ROWID_EQ;
+ return 1.0e9;
+ }
+ }
+
+ /* Check for constraints on a range of rowids
+ */
+ pTerm = findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE|WO_GT|WO_GE, 0);
+ if( pTerm ){
+ int flags;
+ *ppIndex = 0;
+ if( pTerm->operator & (WO_LT|WO_LE) ){
+ flags = WHERE_ROWID_RANGE | WHERE_TOP_LIMIT;
+ if( findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0) ){
+ flags |= WHERE_BTM_LIMIT;
+ }
+ }else{
+ flags = WHERE_ROWID_RANGE | WHERE_BTM_LIMIT;
+ if( findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE, 0) ){
+ flags |= WHERE_TOP_LIMIT;
+ }
+ }
+ if( pOrderBy && sortableByRowid(iCur, pOrderBy, &rev) ){
+ flags |= WHERE_ORDERBY;
+ if( rev ) flags |= WHERE_REVERSE;
+ }
+ bestScore = 99.0;
+ bestFlags = flags;
+ }
+
+ /* Look at each index.
+ */
+ for(pProbe=pSrc->pTab->pIndex; pProbe; pProbe=pProbe->pNext){
+ int i;
+ int nEq;
+ int usesIN = 0;
+ int flags;
+ double score = 0.0;
+
+ /* Count the number of columns in the index that are satisfied
+ ** by x=EXPR constraints or x IN (...) constraints.
+ */
+ 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;
+ if( pTerm->operator==WO_IN ){
+ if( i==0 ) usesIN = 1;
+ break;
+ }
+ }
+ nEq = i + usesIN;
+ score = i*100.0 + usesIN*50.0;
+
+ /* The optimization type is RANGE if there are no == or IN constraints
+ */
+ if( usesIN || nEq ){
+ flags = WHERE_COLUMN_EQ;
+ }else{
+ flags = WHERE_COLUMN_RANGE;
+ }
+
+ /* Look for range constraints
+ */
+ if( !usesIN && 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 ){
+ score += 20.0;
+ flags = WHERE_COLUMN_RANGE;
+ if( pTerm->operator & (WO_LT|WO_LE) ){
+ flags |= WHERE_TOP_LIMIT;
+ if( findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pProbe) ){
+ flags |= WHERE_BTM_LIMIT;
+ score += 20.0;
+ }
+ }else{
+ flags |= WHERE_BTM_LIMIT;
+ if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pProbe) ){
+ flags |= WHERE_TOP_LIMIT;
+ score += 20;
+ }
+ }
+ }
+ }
+
+ /* Add extra points if this index can be used to satisfy the ORDER BY
+ ** clause
+ */
+ if( pOrderBy && !usesIN &&
+ isSortingIndex(pParse, pProbe, pSrc->pTab, iCur, pOrderBy, nEq, &rev) ){
+ flags |= WHERE_ORDERBY;
+ score += 10.0;
+ if( rev ) flags |= WHERE_REVERSE;
+ }
+
+ /* Check to see if we can get away with using just the index without
+ ** ever reading the table. If that is the case, then add one bonus
+ ** point to the score.
+ */
+ if( score>0.0 && 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;
+ score += 5;
+ }
+ }
+
+ /* If this index has achieved the best score so far, then use it.
+ */
+ if( score>bestScore ){
+ bestIdx = pProbe;
+ bestScore = score;
+ bestFlags = flags;
+ }
+ }
+
+ /* Disable sorting if we are coming out in rowid order
+ */
+ if( bestIdx==0 && pOrderBy && sortableByRowid(iCur, pOrderBy, &rev) ){
+ bestFlags |= WHERE_ORDERBY;
+ if( rev ) bestFlags |= WHERE_REVERSE;
+ }
+
+
+ /* Report the best result
+ */
+ *ppIndex = bestIdx;
+ *pFlags = bestFlags;
+ return bestScore;
+}
+
/*
** Disable a term in the WHERE clause. Except, do not disable the term
sqlite3IndexAffinityStr(v, pIdx);
}
-/*
-** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
-** where X is a reference to the iColumn of table iCur and <op> is either
-** op1 or op2. Return a pointer to the term.
-*/
-static WhereTerm *findTerm(
- WhereClause *pWC, /* The WHERE clause to be searched */
- int iCur, /* Cursor number of LHS */
- int iColumn, /* Column number of LHS */
- Bitmask loopMask, /* RHS must not overlap with this mask */
- u8 op1, u8 op2 /* Expression must use either of these opcodes */
-){
- WhereTerm *pTerm;
- int k;
- for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){
- u8 op = pTerm->pExpr->op;
- if( pTerm->leftCursor==iCur
- && (pTerm->prereqRight & loopMask)==0
- && pTerm->leftColumn==iColumn
- && (op==op1 || op==op2)
- ){
- break;
- }
- }
- assert( k>0 ); /* The search is always successful */
- return pTerm;
-}
-
/*
** Generate code for an equality term of the WHERE clause. An equality
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 loopMask; /* One bit cleared for each outer loop */
+ Bitmask notReady; /* Cursors that are not yet positioned */
WhereTerm *pTerm; /* A single term in the WHERE clause */
ExprMaskSet maskSet; /* The expression mask set */
- int iDirectEq[BMS]; /* Term of the form ROWID==X for the N-th table */
- int iDirectLt[BMS]; /* Term of the form ROWID<X or ROWID<=X */
- int iDirectGt[BMS]; /* Term of the form ROWID>X or ROWID>=X */
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 */
** contains additional unfactored AND operators.
*/
initMaskSet(&maskSet);
- whereClauseInit(&wc);
+ whereClauseInit(&wc, pParse);
whereSplit(&wc, pWhere);
/* Allocate and initialize the WhereInfo structure that will become the
exprAnalyze(pTabList, &maskSet, &wc.a[i]);
}
- /* Figure out what index to use (if any) for each nested loop.
- ** Make pWInfo->a[i].pIdx point to the index to use for the i-th nested
- ** loop where i==0 is the outer loop and i==pTabList->nSrc-1 is the inner
- ** loop.
- **
- ** If terms exist that use the ROWID of any table, then set the
- ** iDirectEq[], iDirectLt[], or iDirectGt[] elements for that table
- ** to the index of the term containing the ROWID. We always prefer
- ** to use a ROWID which can directly access a table rather than an
- ** index which requires reading an index first to get the rowid then
- ** doing a second read of the actual database table.
- **
- ** Actually, if there are more than 32 tables in the join, only the
- ** first 32 tables are candidates for indices. This is (again) due
- ** to the limit of 32 bits in an integer bitmask.
+ /* Chose the best index to use for each table in the FROM clause
*/
- loopMask = ~(Bitmask)0;
+ notReady = ~(Bitmask)0;
pTabItem = pTabList->a;
pLevel = pWInfo->a;
- for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++,pTabItem++,pLevel++){
- int j;
- int iCur = pTabItem->iCursor; /* The cursor for this table */
- Bitmask mask = getMask(&maskSet, iCur); /* Cursor mask for this table */
- Table *pTab = pTabItem->pTab;
- Index *pIdx;
- Index *pBestIdx = 0;
- int bestScore = 0;
- int bestRev = 0;
-
- /* Check to see if there is an expression that uses only the
- ** ROWID field of this table. For terms of the form ROWID==expr
- ** set iDirectEq[i] to the index of the term. For terms of the
- ** form ROWID<expr or ROWID<=expr set iDirectLt[i] to the term index.
- ** For terms like ROWID>expr or ROWID>=expr set iDirectGt[i].
- **
- ** (Added:) Treat ROWID IN expr like ROWID=expr.
- */
- pLevel->iIdxCur = -1;
- iDirectEq[i] = -1;
- iDirectLt[i] = -1;
- iDirectGt[i] = -1;
- for(pTerm=wc.a, j=0; j<wc.nTerm; j++, pTerm++){
- if( pTerm->leftCursor==iCur && pTerm->leftColumn<0
- && (pTerm->prereqRight & loopMask)==0 ){
- switch( pTerm->pExpr->op ){
- case TK_IN:
- case TK_EQ: iDirectEq[i] = j; break;
- case TK_LE:
- case TK_LT: iDirectLt[i] = j; break;
- case TK_GE:
- case TK_GT: iDirectGt[i] = j; break;
- }
- }
- }
-
- /* If we found a term that tests ROWID with == or IN, that term
- ** will be used to locate the rows in the database table. There
- ** is no need to continue into the code below that looks for
- ** an index. We will always use the ROWID over an index.
- */
- if( iDirectEq[i]>=0 ){
- loopMask &= ~mask;
- pLevel->pIdx = 0;
- continue;
- }
-
- /* Do a search for usable indices. Leave pBestIdx pointing to
- ** the "best" index. pBestIdx is left set to NULL if no indices
- ** are usable.
- **
- ** The best index is the one with the highest score. The score
- ** for the index is determined as follows. For each of the
- ** left-most terms that is fixed by an equality operator, add
- ** 32 to the score. The right-most term of the index may be
- ** constrained by an inequality. Add 4 if for an "x<..." constraint
- ** and add 8 for an "x>..." constraint. If both constraints
- ** are present, add 12.
- **
- ** If the left-most term of the index uses an IN operator
- ** (ex: "x IN (...)") then add 16 to the score.
- **
- ** If an index can be used for sorting, add 2 to the score.
- ** If an index contains all the terms of a table that are ever
- ** used by any expression in the SQL statement, then add 1 to
- ** the score.
- **
- ** This scoring system is designed so that the score can later be
- ** used to determine how the index is used. If the score&0x1c is 0
- ** then all constraints are equalities. If score&0x4 is not 0 then
- ** there is an inequality used as a termination key. (ex: "x<...")
- ** If score&0x8 is not 0 then there is an inequality used as the
- ** start key. (ex: "x>..."). A score or 0x10 is the special case
- ** of an IN operator constraint. (ex: "x IN ...").
- **
- ** The IN operator (as in "<expr> IN (...)") is treated the same as
- ** an equality comparison except that it can only be used on the
- ** left-most column of an index and other terms of the WHERE clause
- ** cannot be used in conjunction with the IN operator to help satisfy
- ** other columns of the index.
- */
- for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
- Bitmask eqMask = 0; /* Index columns covered by an x=... term */
- Bitmask ltMask = 0; /* Index columns covered by an x<... term */
- Bitmask gtMask = 0; /* Index columns covered by an x>... term */
- Bitmask inMask = 0; /* Index columns covered by an x IN .. term */
- Bitmask m;
- int nEq, score, bRev = 0;
-
- if( pIdx->nColumn>sizeof(eqMask)*8 ){
- continue; /* Ignore indices with too many columns to analyze */
- }
- for(pTerm=wc.a, j=0; j<wc.nTerm; j++, pTerm++){
- Expr *pX = pTerm->pExpr;
- CollSeq *pColl = sqlite3ExprCollSeq(pParse, pX->pLeft);
- if( !pColl && pX->pRight ){
- pColl = sqlite3ExprCollSeq(pParse, pX->pRight);
- }
- if( !pColl ){
- pColl = pParse->db->pDfltColl;
- }
- if( pTerm->leftCursor==iCur && (pTerm->prereqRight & loopMask)==0 ){
- int iColumn = pTerm->leftColumn;
- int k;
- char idxaff = iColumn>=0 ? pIdx->pTable->aCol[iColumn].affinity : 0;
- for(k=0; k<pIdx->nColumn; k++){
- /* If the collating sequences or affinities don't match,
- ** ignore this index. */
- if( pColl!=pIdx->keyInfo.aColl[k] ) continue;
- if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue;
- if( pIdx->aiColumn[k]==iColumn ){
- switch( pX->op ){
- case TK_IN: {
- if( k==0 ) inMask |= 1;
- break;
- }
- case TK_EQ: {
- eqMask |= ((Bitmask)1)<<k;
- break;
- }
- case TK_LE:
- case TK_LT: {
- ltMask |= ((Bitmask)1)<<k;
- break;
- }
- case TK_GE:
- case TK_GT: {
- gtMask |= ((Bitmask)1)<<k;
- break;
- }
- default: {
- /* CANT_HAPPEN */
- assert( 0 );
- break;
- }
- }
- break;
- }
- }
- }
- }
-
- /* The following loop ends with nEq set to the number of columns
- ** on the left of the index with == constraints.
- */
- for(nEq=0; nEq<pIdx->nColumn; nEq++){
- m = (((Bitmask)1)<<(nEq+1))-1;
- if( (m & eqMask)!=m ) break;
- }
-
- /* Begin assembling the score
- */
- score = nEq*32; /* Base score is 32 times number of == constraints */
- m = ((Bitmask)1)<<nEq;
- if( m & ltMask ) score+=4; /* Increase score for a < constraint */
- if( m & gtMask ) score+=8; /* Increase score for a > constraint */
- if( score==0 && inMask ) score = 16; /* Default score for IN constraint */
-
- /* Give bonus points if this index can be used for sorting
- */
- if( i==0 && score!=16 && ppOrderBy && *ppOrderBy ){
- int base = pTabList->a[0].iCursor;
- if( isSortingIndex(pParse, pIdx, pTab, base, *ppOrderBy, nEq, &bRev) ){
- score += 2;
- }
- }
-
- /* Check to see if we can get away with using just the index without
- ** ever reading the table. If that is the case, then add one bonus
- ** point to the score.
- */
- if( score && pTabItem->colUsed < (((Bitmask)1)<<(BMS-1)) ){
- for(m=0, j=0; j<pIdx->nColumn; j++){
- int x = pIdx->aiColumn[j];
- if( x<BMS-1 ){
- m |= ((Bitmask)1)<<x;
- }
- }
- if( (pTabItem->colUsed & m)==pTabItem->colUsed ){
- score++;
- }
- }
-
- /* If the score for this index is the best we have seen so far, then
- ** save it
- */
- if( score>bestScore ){
- pBestIdx = pIdx;
- bestScore = score;
- bestRev = bRev;
- }
+ for(i=0; i<pTabList->nSrc; i++, pTabItem++, pLevel++){
+ Index *pBest;
+ int flags;
+ bestIndex(pParse, &wc, pTabItem, notReady,
+ (i==0 && ppOrderBy) ? *ppOrderBy : 0,
+ &pBest, &flags);
+ if( flags & WHERE_ORDERBY ){
+ *ppOrderBy = 0;
}
- pLevel->pIdx = pBestIdx;
- pLevel->score = bestScore;
- pLevel->bRev = bestRev;
- loopMask &= ~mask;
- if( pBestIdx ){
+ pLevel->flags = flags;
+ pLevel->pIdx = pBest;
+ if( pBest ){
pLevel->iIdxCur = pParse->nTab++;
+ }else{
+ pLevel->iIdxCur = -1;
}
- }
-
- /* Check to see if the ORDER BY clause is or can be satisfied by the
- ** use of an index on the first table.
- */
- if( ppOrderBy && *ppOrderBy && pTabList->nSrc>0 ){
- Index *pIdx; /* Index derived from the WHERE clause */
- Table *pTab; /* Left-most table in the FROM clause */
- int bRev = 0; /* True to reverse the output order */
- int iCur; /* Btree-cursor that will be used by pTab */
- WhereLevel *pLevel0 = &pWInfo->a[0];
-
- pTab = pTabList->a[0].pTab;
- pIdx = pLevel0->pIdx;
- iCur = pTabList->a[0].iCursor;
- if( pIdx==0 && sortableByRowid(iCur, *ppOrderBy, &bRev) ){
- /* The ORDER BY clause specifies ROWID order, which is what we
- ** were going to be doing anyway...
- */
- *ppOrderBy = 0;
- pLevel0->bRev = bRev;
- }else if( pLevel0->score==16 ){
- /* If there is already an IN index on the left-most table,
- ** it will not give the correct sort order.
- ** So, pretend that no suitable index is found.
- */
- }else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){
- /* If the left-most column is accessed using its ROWID, then do
- ** not try to sort by index. But do delete the ORDER BY clause
- ** if it is redundant.
- */
- }else if( (pLevel0->score&2)!=0 ){
- /* The index that was selected for searching will cause rows to
- ** appear in sorted order.
- */
- *ppOrderBy = 0;
- }
+ notReady &= ~getMask(&maskSet, pTabItem->iCursor);
}
/* Open all tables in the pTabList and any indices selected for
pTab = pTabItem->pTab;
if( pTab->isTransient || pTab->pSelect ) continue;
- if( (pLevel->score & 1)==0 ){
+ if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){
sqlite3OpenTableForReading(v, pTabItem->iCursor, pTab);
}
pLevel->iTabCur = pTabItem->iCursor;
sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum,
(char*)&pIx->keyInfo, P3_KEYINFO);
}
- if( (pLevel->score & 1)!=0 ){
+ if( (pLevel->flags & WHERE_IDX_ONLY)!=0 ){
sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, pIx->nColumn+1);
}
sqlite3CodeVerifySchema(pParse, pTab->iDb);
if( z==0 ) z = pTab->zName;
n = strlen(z);
if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){
- if( (pLevel->score & 1)!=0 ){
+ if( pLevel->flags & WHERE_IDX_ONLY ){
strcpy(&sqlite3_query_plan[nQPlan], "{}");
nQPlan += 2;
}else{
/* Generate the code to do the search
*/
- loopMask = ~(Bitmask)0;
+ notReady = ~(Bitmask)0;
pLevel = pWInfo->a;
pTabItem = pTabList->a;
for(i=0; i<pTabList->nSrc; i++, pTabItem++, pLevel++){
- int j, k;
+ 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 */
/* Check to see if it is appropriate to omit the use of the table
** here and use its index instead.
*/
- omitTable = (pLevel->score&1)!=0;
+ omitTable = (pLevel->flags & WHERE_IDX_ONLY)!=0;
/* If this is the right table of a LEFT OUTER JOIN, allocate and
** initialize a memory cell that records if this table matches any
VdbeComment((v, "# init LEFT JOIN no-match flag"));
}
- if( i<ARRAYSIZE(iDirectEq) && (k = iDirectEq[i])>=0 ){
+ 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.
*/
- assert( k<wc.nTerm );
- pTerm = &wc.a[k];
+ 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 );
sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk);
VdbeComment((v, "pk"));
pLevel->op = OP_Noop;
- }else if( pIdx!=0 && pLevel->score>3 && (pLevel->score&0x0c)==0 ){
+ }else if( pLevel->flags & WHERE_COLUMN_EQ ){
/* Case 2: There is an index and all terms of the WHERE clause that
** refer to the index using the "==" or "IN" operators.
*/
int start;
- int nColumn = (pLevel->score+16)/32;
+ int nColumn;
brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
/* For each column of the index, find the term of the WHERE clause that
** constraints that column. If the WHERE clause term is X=expr, then
** generate code to evaluate expr and leave the result on the stack */
- for(j=0; j<nColumn; j++){
- pTerm = findTerm(&wc, iCur, pIdx->aiColumn[j], loopMask, TK_EQ, TK_IN);
- assert( pTerm!=0 );
+ for(j=0; 1; j++){
+ int k = pIdx->aiColumn[j];
+ pTerm = findTerm(&wc, iCur, k, notReady, WO_EQ|WO_IN, pIdx);
+ if( pTerm==0 ) break;
+ if( pTerm->operator==WO_IN && j>0 ) break;
assert( (pTerm->flags & TERM_CODED)==0 );
codeEqualityTerm(pParse, pTerm, brk, pLevel);
+ if( pTerm->operator==WO_IN ){
+ j++;
+ break;
+ }
}
+ nColumn = j;
pLevel->iMem = pParse->nMem++;
cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
buildIndexProbe(v, nColumn, brk, pIdx);
** 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( pLevel->bRev ){
+ if( pLevel->flags & WHERE_REVERSE ){
/* Scan in reverse order */
sqlite3VdbeAddOp(v, OP_MoveLe, iIdxCur, brk);
start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
}
pLevel->p1 = iIdxCur;
pLevel->p2 = start;
- }else if( i<ARRAYSIZE(iDirectLt) && (iDirectLt[i]>=0 || iDirectGt[i]>=0) ){
+ }else if( pLevel->flags & WHERE_ROWID_RANGE ){
/* Case 3: We have an inequality comparison against the ROWID field.
*/
int testOp = OP_Noop;
int start;
- int bRev = pLevel->bRev;
+ WhereTerm *pStart, *pEnd;
+ int bRev = (pLevel->flags & WHERE_REVERSE)!=0;
assert( omitTable==0 );
brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
+ if( pLevel->flags & WHERE_BTM_LIMIT ){
+ pStart = findTerm(&wc, iCur, -1, notReady, WO_GT|WO_GE, 0);
+ assert( pStart!=0 );
+ }else{
+ pStart = 0;
+ }
+ if( pLevel->flags & WHERE_TOP_LIMIT ){
+ pEnd = findTerm(&wc, iCur, -1, notReady, WO_LT|WO_LE, 0);
+ assert( pEnd!=0 );
+ }else{
+ pEnd = 0;
+ }
+ assert( pStart!=0 || pEnd!=0 );
if( bRev ){
- int t = iDirectGt[i];
- iDirectGt[i] = iDirectLt[i];
- iDirectLt[i] = t;
+ pTerm = pStart;
+ pStart = pEnd;
+ pEnd = pTerm;
}
- if( iDirectGt[i]>=0 ){
+ if( pStart ){
Expr *pX;
- k = iDirectGt[i];
- assert( k<wc.nTerm );
- pTerm = &wc.a[k];
- pX = pTerm->pExpr;
+ pX = pStart->pExpr;
assert( pX!=0 );
- assert( pTerm->leftCursor==iCur );
+ 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, pTerm);
+ disableTerm(pLevel, pStart);
}else{
sqlite3VdbeAddOp(v, bRev ? OP_Last : OP_Rewind, iCur, brk);
}
- if( iDirectLt[i]>=0 ){
+ if( pEnd ){
Expr *pX;
- k = iDirectLt[i];
- assert( k<wc.nTerm );
- pTerm = &wc.a[k];
- pX = pTerm->pExpr;
+ pX = pEnd->pExpr;
assert( pX!=0 );
- assert( pTerm->leftCursor==iCur );
+ assert( pEnd->leftCursor==iCur );
sqlite3ExprCode(pParse, pX->pRight);
pLevel->iMem = pParse->nMem++;
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
}else{
testOp = bRev ? OP_Lt : OP_Gt;
}
- disableTerm(pLevel, pTerm);
+ disableTerm(pLevel, pEnd);
}
start = sqlite3VdbeCurrentAddr(v);
pLevel->op = bRev ? OP_Prev : OP_Next;
sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqlite3VdbeAddOp(v, testOp, 'n', brk);
}
- }else if( pIdx==0 ){
- /* Case 4: There is no usable index. We must do a complete
- ** scan of the entire database table.
- */
- int start;
- int opRewind;
-
- assert( omitTable==0 );
- brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
- cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
- if( pLevel->bRev ){
- opRewind = OP_Last;
- pLevel->op = OP_Prev;
- }else{
- opRewind = OP_Rewind;
- pLevel->op = OP_Next;
- }
- sqlite3VdbeAddOp(v, opRewind, iCur, brk);
- start = sqlite3VdbeCurrentAddr(v);
- pLevel->p1 = iCur;
- pLevel->p2 = start;
- }else{
- /* Case 5: The WHERE clause term that refers to the right-most
+ }else if( pLevel->flags & WHERE_COLUMN_RANGE ){
+ /* Case 4: 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
** constraints but an index is selected anyway, in order
** to force the output order to conform to an ORDER BY.
*/
- int score = pLevel->score;
- int nEqColumn = score/32;
+ int nEqColumn;
int start;
int leFlag=0, geFlag=0;
int testOp;
+ int topLimit = (pLevel->flags & WHERE_TOP_LIMIT)!=0;
+ int btmLimit = (pLevel->flags & WHERE_BTM_LIMIT)!=0;
+ int bRev = (pLevel->flags & WHERE_REVERSE)!=0;
/* Evaluate the equality constraints
*/
- for(j=0; j<nEqColumn; j++){
- pTerm = findTerm(&wc, iCur, pIdx->aiColumn[j], loopMask, TK_EQ, TK_EQ);
- assert( pTerm!=0 );
+ for(j=0; 1; j++){
+ int k = pIdx->aiColumn[j];
+ pTerm = findTerm(&wc, iCur, k, notReady, WO_EQ, pIdx);
+ if( pTerm==0 ) break;
assert( (pTerm->flags & TERM_CODED)==0 );
sqlite3ExprCode(pParse, pTerm->pExpr->pRight);
disableTerm(pLevel, pTerm);
}
+ nEqColumn = j;
/* Duplicate the equality term values because they will all be
** used twice: once to make the termination key and once to make the
** 2002-Dec-04: On a reverse-order scan, the so-called "termination"
** key computed here really ends up being the start key.
*/
- if( (score & 4)!=0 ){
+ if( topLimit ){
Expr *pX;
- pTerm = findTerm(&wc, iCur, pIdx->aiColumn[j], loopMask, TK_LT, TK_LE);
+ int k = pIdx->aiColumn[j];
+ pTerm = findTerm(&wc, iCur, k, notReady, WO_LT|WO_LE, pIdx);
assert( pTerm!=0 );
pX = pTerm->pExpr;
assert( (pTerm->flags & TERM_CODED)==0 );
leFlag = 1;
}
if( testOp!=OP_Noop ){
- int nCol = nEqColumn + ((score & 4)!=0);
+ int nCol = nEqColumn + topLimit;
pLevel->iMem = pParse->nMem++;
buildIndexProbe(v, nCol, brk, pIdx);
- if( pLevel->bRev ){
+ if( bRev ){
int op = leFlag ? OP_MoveLe : OP_MoveLt;
sqlite3VdbeAddOp(v, op, iIdxCur, brk);
}else{
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
}
- }else if( pLevel->bRev ){
+ }else if( bRev ){
sqlite3VdbeAddOp(v, OP_Last, iIdxCur, brk);
}
** 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( (score & 8)!=0 ){
+ if( btmLimit ){
Expr *pX;
- pTerm = findTerm(&wc, iCur, pIdx->aiColumn[j], loopMask, TK_GT, TK_GE);
+ int k = pIdx->aiColumn[j];
+ pTerm = findTerm(&wc, iCur, k, notReady, WO_GT|WO_GE, pIdx);
assert( pTerm!=0 );
pX = pTerm->pExpr;
assert( (pTerm->flags & TERM_CODED)==0 );
}else{
geFlag = 1;
}
- if( nEqColumn>0 || (score&8)!=0 ){
- int nCol = nEqColumn + ((score&8)!=0);
+ if( nEqColumn>0 || btmLimit ){
+ int nCol = nEqColumn + btmLimit;
buildIndexProbe(v, nCol, brk, pIdx);
- if( pLevel->bRev ){
+ if( bRev ){
pLevel->iMem = pParse->nMem++;
sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
testOp = OP_IdxLT;
int op = geFlag ? OP_MoveGe : OP_MoveGt;
sqlite3VdbeAddOp(v, op, iIdxCur, brk);
}
- }else if( pLevel->bRev ){
+ }else if( bRev ){
testOp = OP_Noop;
}else{
sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, brk);
if( testOp!=OP_Noop ){
sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqlite3VdbeAddOp(v, testOp, iIdxCur, brk);
- if( (leFlag && !pLevel->bRev) || (!geFlag && pLevel->bRev) ){
+ if( (leFlag && !bRev) || (!geFlag && bRev) ){
sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC);
}
}
sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0);
- sqlite3VdbeAddOp(v, OP_IdxIsNull, nEqColumn + ((score&4)!=0), cont);
+ sqlite3VdbeAddOp(v, OP_IdxIsNull, nEqColumn + topLimit, 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 = pLevel->bRev ? OP_Prev : OP_Next;
+ pLevel->op = bRev ? OP_Prev : OP_Next;
pLevel->p1 = iIdxCur;
pLevel->p2 = start;
+ }else{
+ /* Case 5: There is no usable index. We must do a complete
+ ** scan of the entire table.
+ */
+ int start;
+ int opRewind;
+
+ assert( omitTable==0 );
+ brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
+ cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
+ if( pLevel->flags & WHERE_REVERSE ){
+ opRewind = OP_Last;
+ pLevel->op = OP_Prev;
+ }else{
+ opRewind = OP_Rewind;
+ pLevel->op = OP_Next;
+ }
+ sqlite3VdbeAddOp(v, opRewind, iCur, brk);
+ start = sqlite3VdbeCurrentAddr(v);
+ pLevel->p1 = iCur;
+ pLevel->p2 = start;
}
- loopMask &= ~getMask(&maskSet, iCur);
+ 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 & loopMask)!=0 ) continue;
+ if( (pTerm->prereqAll & notReady)!=0 ) continue;
pE = pTerm->pExpr;
assert( pE!=0 );
if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
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 & loopMask)!=0 ) continue;
+ if( (pTerm->prereqAll & notReady)!=0 ) continue;
assert( pTerm->pExpr );
sqlite3ExprIfFalse(pParse, pTerm->pExpr, cont, 1);
pTerm->flags |= TERM_CODED;
Table *pTab = pTabItem->pTab;
assert( pTab!=0 );
if( pTab->isTransient || pTab->pSelect ) continue;
- if( (pLevel->score & 1)==0 ){
+ if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){
sqlite3VdbeAddOp(v, OP_Close, pTabItem->iCursor, 0);
}
if( pLevel->pIdx!=0 ){
** that reference the table and converts them into opcodes that
** reference the index.
*/
- if( pLevel->score & 1 ){
+ if( pLevel->flags & WHERE_IDX_ONLY ){
int i, j, last;
VdbeOp *pOp;
Index *pIdx = pLevel->pIdx;
sqliteFree(pWInfo);
return;
}
+
+
+/*
+** Delete a list of WhereIdx structures.
+*/
+void sqlite3WhereIdxListDelete(WhereIdx *p){
+ WhereIdx *pNext;
+ while( p ){
+ pNext = p->pNext;
+ sqliteFree(p);
+ p = pNext;
+ }
+}
projects / thirdparty / sqlite.git / commitdiff
