#define WHERE_BTM_LIMIT 0x00200000 /* x>EXPR or x>=EXPR constraint */
#define WHERE_BOTH_LIMIT 0x00300000 /* Both x>EXPR and x<EXPR */
#define WHERE_IDX_ONLY 0x00400000 /* Use index only - omit table */
-#define WHERE_ORDERBY 0x00800000 /* Output will appear in correct order */
+#define WHERE_ORDERED 0x00800000 /* Output will appear in correct order */
#define WHERE_REVERSE 0x01000000 /* Scan in reverse order */
#define WHERE_UNIQUE 0x02000000 /* Selects no more than one row */
#define WHERE_ALL_UNIQUE 0x04000000 /* This and all prior have one row */
WhereCost cost; /* Lowest cost query plan */
};
+/*
+** Return TRUE if the probe cost is less than the baseline cost
+*/
+static int compareCost(const WhereCost *pProbe, const WhereCost *pBaseline){
+ if( pProbe->rCost<pBaseline->rCost ) return 1;
+ if( pProbe->rCost>pBaseline->rCost ) return 0;
+ if( pProbe->plan.nOBSat>pBaseline->plan.nOBSat ) return 1;
+ if( pProbe->plan.nRow<pBaseline->plan.nRow ) return 1;
+ return 0;
+}
+
/*
** Initialize a preallocated WhereClause structure.
*/
p->cost.rCost = rTotal;
p->cost.used = used;
p->cost.plan.nRow = nRow;
+ p->cost.plan.nOBSat = p->i ? p->aLevel[p->i-1].plan.nOBSat : 0;
p->cost.plan.wsFlags = flags;
p->cost.plan.u.pTerm = pTerm;
}
}
p->cost.plan.u.pVtabIdx = pIdxInfo;
if( pIdxInfo->orderByConsumed ){
- p->cost.plan.wsFlags |= WHERE_ORDERBY;
+ p->cost.plan.wsFlags |= WHERE_ORDERED;
+ p->cost.plan.nOBSat = nOrderBy;
+ }else{
+ p->cost.plan.nOBSat = p->i ? p->aLevel[p->i-1].plan.nOBSat : 0;
}
p->cost.plan.nEq = 0;
pIdxInfo->nOrderBy = nOrderBy;
if( (pLevel->plan.wsFlags & WHERE_ALL_UNIQUE)!=0 ){
return 1;
}
- if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
- pIdx = pLevel->plan.u.pIdx;
+ if( (pLevel->plan.wsFlags & WHERE_ORDERED)==0 ){
+ return 0;
+ }
+ if( (pIdx = pLevel->plan.u.pIdx)!=0 ){
if( iCol<0 ){
sortOrder = 0;
testcase( (pLevel->plan.wsFlags & WHERE_REVERSE)!=0 );
nPriorSat = p->aLevel[p->i-1].plan.nOBSat;
if( OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ) return nPriorSat;
}
- if( p->i==0 || (p->aLevel[p->i-1].plan.wsFlags & WHERE_ALL_UNIQUE)!=0 ){
+ if( nEqCol==0 ){
+ if( p->i && (p->aLevel[p->i-1].plan.wsFlags & WHERE_ORDERED)==0 ){
+ return nPriorSat;
+ }
+ nEqOneRow = 0;
+ }else if( p->i==0 || (p->aLevel[p->i-1].plan.wsFlags & WHERE_ALL_UNIQUE)!=0 ){
nEqOneRow = nEqCol;
}else{
- if( nEqCol==0 ) return nPriorSat;
sortOrder = bOuterRev;
nEqOneRow = -1;
}
*/
for(; pProbe; pIdx=pProbe=pProbe->pNext){
const tRowcnt * const aiRowEst = pProbe->aiRowEst;
- double cost; /* Cost of using pProbe */
- double nRow; /* Estimated number of rows in result set */
+ WhereCost pc; /* Cost of using pProbe */
double log10N = (double)1; /* base-10 logarithm of nRow (inexact) */
int bRev = 2; /* 0=forward scan. 1=reverse. 2=undecided */
- int wsFlags = 0;
- Bitmask used = 0;
+ memset(&pc, 0, sizeof(pc));
/* The following variables are populated based on the properties of
** index being evaluated. They are then used to determine the expected
** cost and number of rows returned.
**
- ** nEq:
+ ** pc.plan.nEq:
** Number of equality terms that can be implemented using the index.
** In other words, the number of initial fields in the index that
** are used in == or IN or NOT NULL constraints of the WHERE clause.
** SELECT a, b FROM tbl WHERE a = 1;
** SELECT a, b, c FROM tbl WHERE a = 1;
*/
- int nEq; /* Number of == or IN terms matching index */
int nOrdered; /* Number of ordered terms matching index */
int bInEst = 0; /* True if "x IN (SELECT...)" seen */
int nInMul = 1; /* Number of distinct equalities to lookup */
int bSort; /* True if external sort required */
int bDist; /* True if index cannot help with DISTINCT */
int bLookup = 0; /* True if not a covering index */
- int nOBSat = 0; /* Number of ORDER BY terms satisfied */
+ int nPriorSat; /* ORDER BY terms satisfied by outer loops */
int nOrderBy; /* Number of ORDER BY terms */
WhereTerm *pTerm; /* A single term of the WHERE clause */
#ifdef SQLITE_ENABLE_STAT3
#endif
nOrderBy = p->pOrderBy ? p->pOrderBy->nExpr : 0;
- bSort = nOrderBy>0 && (p->i==0 || p->aLevel[p->i-1].plan.nOBSat<nOrderBy);
- bDist = p->i==0 && p->pDistinct!=0;
+ if( p->i ){
+ nPriorSat = pc.plan.nOBSat = p->aLevel[p->i-1].plan.nOBSat;
+ bSort = nPriorSat<nOrderBy;
+ bDist = 0;
+ }else{
+ nPriorSat = pc.plan.nOBSat = 0;
+ bSort = nOrderBy>0;
+ bDist = p->pDistinct!=0;
+ }
- /* Determine the values of nEq and nInMul */
- for(nEq=nOrdered=0; nEq<pProbe->nColumn; nEq++){
- int j = pProbe->aiColumn[nEq];
+ /* Determine the values of pc.plan.nEq and nInMul */
+ for(pc.plan.nEq=nOrdered=0; pc.plan.nEq<pProbe->nColumn; pc.plan.nEq++){
+ int j = pProbe->aiColumn[pc.plan.nEq];
pTerm = findTerm(pWC, iCur, j, p->notReady, eqTermMask, pIdx);
if( pTerm==0 ) break;
- wsFlags |= (WHERE_COLUMN_EQ|WHERE_ROWID_EQ);
+ pc.plan.wsFlags |= (WHERE_COLUMN_EQ|WHERE_ROWID_EQ);
testcase( pTerm->pWC!=pWC );
if( pTerm->eOperator & WO_IN ){
Expr *pExpr = pTerm->pExpr;
- wsFlags |= WHERE_COLUMN_IN;
+ pc.plan.wsFlags |= WHERE_COLUMN_IN;
if( ExprHasProperty(pExpr, EP_xIsSelect) ){
/* "x IN (SELECT ...)": Assume the SELECT returns 25 rows */
nInMul *= 25;
nInMul *= pExpr->x.pList->nExpr;
}
}else if( pTerm->eOperator & WO_ISNULL ){
- wsFlags |= WHERE_COLUMN_NULL;
- if( nEq==nOrdered ) nOrdered++;
- }else if( bSort && nEq==nOrdered && isOrderedTerm(p, pTerm, &bRev) ){
+ pc.plan.wsFlags |= WHERE_COLUMN_NULL;
+ if( pc.plan.nEq==nOrdered ) nOrdered++;
+ }else if( bSort && pc.plan.nEq==nOrdered && isOrderedTerm(p, pTerm, &bRev) ){
nOrdered++;
}
#ifdef SQLITE_ENABLE_STAT3
- if( nEq==0 && pProbe->aSample ) pFirstTerm = pTerm;
+ if( pc.plan.nEq==0 && pProbe->aSample ) pFirstTerm = pTerm;
#endif
- used |= pTerm->prereqRight;
+ pc.used |= pTerm->prereqRight;
}
/* If the index being considered is UNIQUE, and there is an equality
** indicate this to the caller.
**
** Otherwise, if the search may find more than one row, test to see if
- ** there is a range constraint on indexed column (nEq+1) that can be
+ ** there is a range constraint on indexed column (pc.plan.nEq+1) that can be
** optimized using the index.
*/
- if( nEq==pProbe->nColumn && pProbe->onError!=OE_None ){
- testcase( wsFlags & WHERE_COLUMN_IN );
- testcase( wsFlags & WHERE_COLUMN_NULL );
- if( (wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0 ){
- wsFlags |= WHERE_UNIQUE;
+ if( pc.plan.nEq==pProbe->nColumn && pProbe->onError!=OE_None ){
+ testcase( pc.plan.wsFlags & WHERE_COLUMN_IN );
+ testcase( pc.plan.wsFlags & WHERE_COLUMN_NULL );
+ if( (pc.plan.wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0 ){
+ pc.plan.wsFlags |= WHERE_UNIQUE;
if( p->i==0 || (p->aLevel[p->i-1].plan.wsFlags & WHERE_ALL_UNIQUE)!=0 ){
- wsFlags |= WHERE_ALL_UNIQUE;
+ pc.plan.wsFlags |= WHERE_ALL_UNIQUE;
}
}
}else if( pProbe->bUnordered==0 ){
- int j = (nEq==pProbe->nColumn ? -1 : pProbe->aiColumn[nEq]);
+ int j;
+ j = (pc.plan.nEq==pProbe->nColumn ? -1 : pProbe->aiColumn[pc.plan.nEq]);
if( findTerm(pWC, iCur, j, p->notReady, WO_LT|WO_LE|WO_GT|WO_GE, pIdx) ){
WhereTerm *pTop, *pBtm;
pTop = findTerm(pWC, iCur, j, p->notReady, WO_LT|WO_LE, pIdx);
pBtm = findTerm(pWC, iCur, j, p->notReady, WO_GT|WO_GE, pIdx);
- whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &rangeDiv);
+ whereRangeScanEst(pParse, pProbe, pc.plan.nEq, pBtm, pTop, &rangeDiv);
if( pTop ){
nBound = 1;
- wsFlags |= WHERE_TOP_LIMIT;
- used |= pTop->prereqRight;
+ pc.plan.wsFlags |= WHERE_TOP_LIMIT;
+ pc.used |= pTop->prereqRight;
testcase( pTop->pWC!=pWC );
}
if( pBtm ){
nBound++;
- wsFlags |= WHERE_BTM_LIMIT;
- used |= pBtm->prereqRight;
+ pc.plan.wsFlags |= WHERE_BTM_LIMIT;
+ pc.used |= pBtm->prereqRight;
testcase( pBtm->pWC!=pWC );
}
- wsFlags |= (WHERE_COLUMN_RANGE|WHERE_ROWID_RANGE);
+ pc.plan.wsFlags |= (WHERE_COLUMN_RANGE|WHERE_ROWID_RANGE);
}
}
/* If there is an ORDER BY clause and the index being considered will
** naturally scan rows in the required order, set the appropriate flags
- ** in wsFlags. Otherwise, if there is an ORDER BY clause but the index
- ** will scan rows in a different order, set the bSort variable. */
+ ** in pc.plan.wsFlags. Otherwise, if there is an ORDER BY clause but
+ ** the index will scan rows in a different order, set the bSort
+ ** variable. */
assert( bRev>=0 && bRev<=2 );
if( bSort ){
testcase( bRev==0 );
testcase( bRev==1 );
testcase( bRev==2 );
- nOBSat = isSortingIndex(p, pProbe, iCur, nOrdered,
- wsFlags, bRev&1, &bRev);
- if( nOrderBy==nOBSat ){
+ pc.plan.nOBSat = isSortingIndex(p, pProbe, iCur, nOrdered,
+ pc.plan.wsFlags, bRev&1, &bRev);
+ if( nPriorSat<pc.plan.nOBSat || (pc.plan.wsFlags & WHERE_UNIQUE)!=0 ){
+ pc.plan.wsFlags |= WHERE_ORDERED;
+ }
+ if( nOrderBy==pc.plan.nOBSat ){
bSort = 0;
- wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_ORDERBY;
+ pc.plan.wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE;
}
- if( bRev & 1 ) wsFlags |= WHERE_REVERSE;
+ if( bRev & 1 ) pc.plan.wsFlags |= WHERE_REVERSE;
}
/* If there is a DISTINCT qualifier and this index will scan rows in
** order of the DISTINCT expressions, clear bDist and set the appropriate
- ** flags in wsFlags. */
+ ** flags in pc.plan.wsFlags. */
if( bDist
- && isDistinctIndex(pParse, pWC, pProbe, iCur, p->pDistinct, nEq)
- && (wsFlags & WHERE_COLUMN_IN)==0
+ && isDistinctIndex(pParse, pWC, pProbe, iCur, p->pDistinct, pc.plan.nEq)
+ && (pc.plan.wsFlags & WHERE_COLUMN_IN)==0
){
bDist = 0;
- wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_DISTINCT;
+ pc.plan.wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_DISTINCT;
}
/* If currently calculating the cost of using an index (not the IPK
** index), determine if all required column data may be obtained without
** using the main table (i.e. if the index is a covering
** index for this query). If it is, set the WHERE_IDX_ONLY flag in
- ** wsFlags. Otherwise, set the bLookup variable to true. */
+ ** pc.plan.wsFlags. Otherwise, set the bLookup variable to true. */
if( pIdx ){
Bitmask m = pSrc->colUsed;
int j;
}
}
if( m==0 ){
- wsFlags |= WHERE_IDX_ONLY;
+ pc.plan.wsFlags |= WHERE_IDX_ONLY;
}else{
bLookup = 1;
}
** Estimate the number of rows of output. For an "x IN (SELECT...)"
** constraint, do not let the estimate exceed half the rows in the table.
*/
- nRow = (double)(aiRowEst[nEq] * nInMul);
- if( bInEst && nRow*2>aiRowEst[0] ){
- nRow = aiRowEst[0]/2;
- nInMul = (int)(nRow / aiRowEst[nEq]);
+ pc.plan.nRow = (double)(aiRowEst[pc.plan.nEq] * nInMul);
+ if( bInEst && pc.plan.nRow*2>aiRowEst[0] ){
+ pc.plan.nRow = aiRowEst[0]/2;
+ nInMul = (int)(pc.plan.nRow / aiRowEst[pc.plan.nEq]);
}
#ifdef SQLITE_ENABLE_STAT3
** to get a better estimate on the number of rows based on
** VALUE and how common that value is according to the histogram.
*/
- if( nRow>(double)1 && nEq==1 && pFirstTerm!=0 && aiRowEst[1]>1 ){
+ if( pc.plan.nRow>(double)1 && pc.plan.nEq==1
+ && pFirstTerm!=0 && aiRowEst[1]>1 ){
assert( (pFirstTerm->eOperator & (WO_EQ|WO_ISNULL|WO_IN))!=0 );
if( pFirstTerm->eOperator & (WO_EQ|WO_ISNULL) ){
testcase( pFirstTerm->eOperator==WO_EQ );
testcase( pFirstTerm->eOperator==WO_ISNULL );
- whereEqualScanEst(pParse, pProbe, pFirstTerm->pExpr->pRight, &nRow);
+ whereEqualScanEst(pParse, pProbe, pFirstTerm->pExpr->pRight,
+ &pc.plan.nRow);
}else if( bInEst==0 ){
assert( pFirstTerm->eOperator==WO_IN );
- whereInScanEst(pParse, pProbe, pFirstTerm->pExpr->x.pList, &nRow);
+ whereInScanEst(pParse, pProbe, pFirstTerm->pExpr->x.pList,
+ &pc.plan.nRow);
}
}
#endif /* SQLITE_ENABLE_STAT3 */
/* Adjust the number of output rows and downward to reflect rows
** that are excluded by range constraints.
*/
- nRow = nRow/rangeDiv;
- if( nRow<1 ) nRow = 1;
+ pc.plan.nRow = pc.plan.nRow/rangeDiv;
+ if( pc.plan.nRow<1 ) pc.plan.nRow = 1;
/* Experiments run on real SQLite databases show that the time needed
** to do a binary search to locate a row in a table or index is roughly
** So this computation assumes table records are about twice as big
** as index records
*/
- if( (wsFlags&~WHERE_REVERSE)==WHERE_IDX_ONLY
+ if( (pc.plan.wsFlags&~(WHERE_REVERSE|WHERE_ORDERED))==WHERE_IDX_ONLY
&& (pWC->wctrlFlags & WHERE_ONEPASS_DESIRED)==0
&& sqlite3GlobalConfig.bUseCis
&& OptimizationEnabled(pParse->db, SQLITE_CoverIdxScan)
** A full-scan of the index might be a little faster than a full-scan
** of the table, so give this case a cost slightly less than a table
** scan. */
- cost = aiRowEst[0]*3 + pProbe->nColumn;
- wsFlags |= WHERE_COVER_SCAN|WHERE_COLUMN_RANGE;
- }else if( (wsFlags & WHERE_NOT_FULLSCAN)==0 ){
+ pc.rCost = aiRowEst[0]*3 + pProbe->nColumn;
+ pc.plan.wsFlags |= WHERE_COVER_SCAN|WHERE_COLUMN_RANGE;
+ }else if( (pc.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ){
/* The cost of a full table scan is a number of move operations equal
** to the number of rows in the table.
**
** decision and one which we expect to revisit in the future. But
** it seems to be working well enough at the moment.
*/
- cost = aiRowEst[0]*4;
- wsFlags &= ~WHERE_IDX_ONLY;
+ pc.rCost = aiRowEst[0]*4;
+ pc.plan.wsFlags &= ~WHERE_IDX_ONLY;
}else{
log10N = estLog(aiRowEst[0]);
- cost = nRow;
+ pc.rCost = pc.plan.nRow;
if( pIdx ){
if( bLookup ){
/* For an index lookup followed by a table lookup:
** + nRow steps through the index
** + nRow table searches to lookup the table entry using the rowid
*/
- cost += (nInMul + nRow)*log10N;
+ pc.rCost += (nInMul + pc.plan.nRow)*log10N;
}else{
/* For a covering index:
** nInMul index searches to find the initial entry
** + nRow steps through the index
*/
- cost += nInMul*log10N;
+ pc.rCost += nInMul*log10N;
}
}else{
/* For a rowid primary key lookup:
** nInMult table searches to find the initial entry for each range
** + nRow steps through the table
*/
- cost += nInMul*log10N;
+ pc.rCost += nInMul*log10N;
}
}
** difference and select C of 3.0.
*/
if( bSort ){
- cost += nRow*estLog(nRow*(nOrderBy - nOBSat)/nOrderBy)*3;
+ double m = estLog(pc.plan.nRow*(nOrderBy - pc.plan.nOBSat)/nOrderBy);
+ m *= (double)(pc.plan.nOBSat ? 2 : 3);
+ pc.rCost += pc.plan.nRow*m;
}
if( bDist ){
- cost += nRow*estLog(nRow)*3;
+ pc.rCost += pc.plan.nRow*estLog(pc.plan.nRow)*3;
}
/**** Cost of using this index has now been computed ****/
** might be selected even when there exists an optimal index that has
** no such dependency.
*/
- if( nRow>2 && cost<=p->cost.rCost ){
+ if( pc.plan.nRow>2 && pc.rCost<=p->cost.rCost ){
int k; /* Loop counter */
- int nSkipEq = nEq; /* Number of == constraints to skip */
+ int nSkipEq = pc.plan.nEq; /* Number of == constraints to skip */
int nSkipRange = nBound; /* Number of < constraints to skip */
Bitmask thisTab; /* Bitmap for pSrc */
thisTab = getMask(pWC->pMaskSet, iCur);
- for(pTerm=pWC->a, k=pWC->nTerm; nRow>2 && k; k--, pTerm++){
+ for(pTerm=pWC->a, k=pWC->nTerm; pc.plan.nRow>2 && k; k--, pTerm++){
if( pTerm->wtFlags & TERM_VIRTUAL ) continue;
if( (pTerm->prereqAll & p->notValid)!=thisTab ) continue;
if( pTerm->eOperator & (WO_EQ|WO_IN|WO_ISNULL) ){
if( nSkipEq ){
- /* Ignore the first nEq equality matches since the index
+ /* Ignore the first pc.plan.nEq equality matches since the index
** has already accounted for these */
nSkipEq--;
}else{
/* Assume each additional equality match reduces the result
** set size by a factor of 10 */
- nRow /= 10;
+ pc.plan.nRow /= 10;
}
}else if( pTerm->eOperator & (WO_LT|WO_LE|WO_GT|WO_GE) ){
if( nSkipRange ){
** more selective intentionally because of the subjective
** observation that indexed range constraints really are more
** selective in practice, on average. */
- nRow /= 3;
+ pc.plan.nRow /= 3;
}
}else if( pTerm->eOperator!=WO_NOOP ){
/* Any other expression lowers the output row count by half */
- nRow /= 2;
+ pc.plan.nRow /= 2;
}
}
- if( nRow<2 ) nRow = 2;
+ if( pc.plan.nRow<2 ) pc.plan.nRow = 2;
}
" notReady=0x%llx log10N=%.1f nRow=%.1f cost=%.1f\n"
" used=0x%llx nOrdered=%d nOBSat=%d\n",
pSrc->pTab->zName, (pIdx ? pIdx->zName : "ipk"),
- nEq, nInMul, (int)rangeDiv, bSort, bLookup, wsFlags,
- p->notReady, log10N, nRow, cost, used, nOrdered, nOBSat
+ pc.plan.nEq, nInMul, (int)rangeDiv, bSort, bLookup, pc.plan.wsFlags,
+ p->notReady, log10N, pc.plan.nRow, pc.rCost, pc.used, nOrdered,
+ pc.plan.nOBSat
));
/* If this index is the best we have seen so far, then record this
- ** index and its cost in the pCost structure.
+ ** index and its cost in the p->cost structure.
*/
- if( (!pIdx || wsFlags)
- && (cost<p->cost.rCost || (cost<=p->cost.rCost && nRow<p->cost.plan.nRow))
- ){
- p->cost.rCost = cost;
- p->cost.used = used;
- p->cost.plan.nRow = nRow;
- p->cost.plan.wsFlags = (wsFlags&wsFlagMask);
- p->cost.plan.nEq = nEq;
- p->cost.plan.nOBSat = nOBSat;
+ if( (!pIdx || pc.plan.wsFlags) && compareCost(&pc, &p->cost) ){
+ p->cost = pc;
+ p->cost.plan.wsFlags &= wsFlagMask;
p->cost.plan.u.pIdx = pIdx;
}
p->cost.plan.wsFlags |= WHERE_REVERSE;
}
- assert( p->pOrderBy || (p->cost.plan.wsFlags&WHERE_ORDERBY)==0 );
+ assert( p->pOrderBy || (p->cost.plan.wsFlags&WHERE_ORDERED)==0 );
assert( p->cost.plan.u.pIdx==0 || (p->cost.plan.wsFlags&WHERE_ROWID_EQ)==0 );
assert( pSrc->pIndex==0
|| p->cost.plan.u.pIdx==0
|| p->cost.plan.u.pIdx==pSrc->pIndex
);
- WHERETRACE(("best index is: %s\n",
- ((p->cost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ? "none" :
- p->cost.plan.u.pIdx ? p->cost.plan.u.pIdx->zName : "ipk")
- ));
+ WHERETRACE(("best index is: %s\n",
+ p->cost.plan.u.pIdx ? p->cost.plan.u.pIdx->zName : "ipk"));
bestOrClauseIndex(p);
bestAutomaticIndex(p);
** this requires some special handling.
*/
if( (wctrlFlags&WHERE_ORDERBY_MIN)!=0
- && (pLevel->plan.wsFlags&WHERE_ORDERBY)
+ && (pLevel->plan.wsFlags&WHERE_ORDERED)
&& (pIdx->nColumn>nEq)
){
/* assert( pOrderBy->nExpr==1 ); */
** The NEVER() comes about because rule (2) above prevents
** An indexable full-table-scan from reaching rule (3).
**
- ** (4) The plan cost must be lower than prior plans or else the
- ** cost must be the same and the number of rows must be lower.
+ ** (4) The plan cost must be lower than prior plans, where "cost"
+ ** is defined by the compareCost() function above.
*/
if( (sWBI.cost.used&sWBI.notValid)==0 /* (1) */
&& (bestJ<0 || (notIndexed&m)!=0 /* (2) */
|| (sWBI.cost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0)
&& (nUnconstrained==0 || sWBI.pSrc->pIndex==0 /* (3) */
|| NEVER((sWBI.cost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0))
- && (bestJ<0 || sWBI.cost.rCost<bestPlan.rCost /* (4) */
- || (sWBI.cost.rCost<=bestPlan.rCost
- && sWBI.cost.plan.nRow<bestPlan.plan.nRow))
+ && (bestJ<0 || compareCost(&sWBI.cost, &bestPlan)) /* (4) */
){
- WHERETRACE(("=== table %d (%s) is best so far"
- " with cost=%.1f, nRow=%.1f, nOBSat=%d\n",
+ WHERETRACE(("=== table %d (%s) is best so far\n"
+ " cost=%.1f, nRow=%.1f, nOBSat=%d, wsFlags=%08x\n",
j, sWBI.pSrc->pTab->zName,
sWBI.cost.rCost, sWBI.cost.plan.nRow,
- sWBI.cost.plan.nOBSat));
+ sWBI.cost.plan.nOBSat, sWBI.cost.plan.wsFlags));
bestPlan = sWBI.cost;
bestJ = j;
}
assert( bestJ>=0 );
assert( sWBI.notValid & getMask(pMaskSet, pTabList->a[bestJ].iCursor) );
WHERETRACE(("*** Optimizer selects table %d (%s) for loop %d with:\n"
- " cost=%.1f, nRow=%.1f, nOBSat=%d wsFlags=0x%08x\n",
+ " cost=%.1f, nRow=%.1f, nOBSat=%d, wsFlags=0x%08x\n",
bestJ, pTabList->a[bestJ].pTab->zName,
pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow,
bestPlan.plan.nOBSat, bestPlan.plan.wsFlags));
- if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 ){
- pWInfo->nOBSat = pOrderBy->nExpr;
- }
if( (bestPlan.plan.wsFlags & WHERE_DISTINCT)!=0 ){
assert( pWInfo->eDistinct==0 );
pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
if( pParse->nErr || db->mallocFailed ){
goto whereBeginError;
}
+ if( nTabList ){
+ pLevel--;
+ pWInfo->nOBSat = pLevel->plan.nOBSat;
+ }else{
+ pWInfo->nOBSat = 0;
+ }
/* If the total query only selects a single row, then the ORDER BY
** clause is irrelevant.
*/
if( (andFlags & WHERE_UNIQUE)!=0 && pOrderBy ){
+ assert( nTabList==0 || (pLevel->plan.wsFlags & WHERE_ALL_UNIQUE)!=0 );
pWInfo->nOBSat = pOrderBy->nExpr;
}
projects / thirdparty / sqlite.git / commitdiff
