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Performance improvements:

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Avoid unnecessary seeks when doing a single-row UPDATE on a WITHOUT ROWID
table.

FossilOrigin-Name: 6f187a0fb1b09ebc4732c4afbf3c813f82e069f1
This commit is contained in:
drh
2013-11-08 15:19:46 +00:00
parent 81897bb14e
commit fc8d4f96b4
6 changed files with 91 additions and 33 deletions
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69
src/where.c
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@@ -409,6 +409,7 @@ struct WhereInfo {
int iContinue; /* Jump here to continue with next record */
int iBreak; /* Jump here to break out of the loop */
int savedNQueryLoop; /* pParse->nQueryLoop outside the WHERE loop */
int aiCurOnePass[2]; /* OP_OpenWrite cursors for the ONEPASS opt */
WhereMaskSet sMaskSet; /* Map cursor numbers to bitmasks */
WhereClause sWC; /* Decomposition of the WHERE clause */
WhereLevel a[1]; /* Information about each nest loop in WHERE */
@@ -501,8 +502,19 @@ int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
** Return TRUE if an UPDATE or DELETE statement can operate directly on
** the rowids returned by a WHERE clause. Return FALSE if doing an
** UPDATE or DELETE might change subsequent WHERE clause results.
**
** If the ONEPASS optimization is used (if this routine returns true)
** then also write the indices of open cursors used by ONEPASS
** into aiCur[0] and aiCur[1]. iaCur[0] gets the cursor of the data
** table and iaCur[1] gets the cursor used by an auxiliary index.
** Either value may be -1, indicating that cursor is not used.
** Any cursors returned will have been opened for writing.
**
** aiCur[0] and aiCur[1] both get -1 if the where-clause logic is
** unable to use the ONEPASS optimization.
*/
int sqlite3WhereOkOnePass(WhereInfo *pWInfo){
int sqlite3WhereOkOnePass(WhereInfo *pWInfo, int *aiCur){
memcpy(aiCur, pWInfo->aiCurOnePass, sizeof(int)*2);
return pWInfo->okOnePass;
}
@@ -3152,7 +3164,7 @@ static Bitmask codeOneLoopStart(
bRev = (pWInfo->revMask>>iLevel)&1;
omitTable = (pLoop->wsFlags & WHERE_IDX_ONLY)!=0
&& (pWInfo->wctrlFlags & WHERE_FORCE_TABLE)==0;
VdbeNoopComment((v, "Begin Join Loop %d", iLevel));
VdbeNoopComment((v, "Begin WHERE-Loop %d: %s", iLevel,pTabItem->pTab->zName));
/* Create labels for the "break" and "continue" instructions
** for the current loop. Jump to addrBrk to break out of a loop.
@@ -5694,6 +5706,14 @@ static int whereShortCut(WhereLoopBuilder *pBuilder){
** if the WHERE_GROUPBY flag is set in wctrlFlags) 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 pOrderBy is NULL.
**
** The iIdxCur parameter is the cursor number of an index. If
** WHERE_ONETABLE_ONLY is set, iIdxCur is the cursor number of an index
** to use for OR clause processing. The WHERE clause should use this
** specific cursor. If WHERE_ONEPASS_DESIRED is set, then iIdxCur is
** the first cursor in an array of cursors for all indices. iIdxCur should
** be used to compute the appropriate cursor depending on which index is
** used.
*/
WhereInfo *sqlite3WhereBegin(
Parse *pParse, /* The parser context */
@@ -5759,6 +5779,7 @@ WhereInfo *sqlite3WhereBegin(
pWInfo = 0;
goto whereBeginError;
}
pWInfo->aiCurOnePass[0] = pWInfo->aiCurOnePass[1] = -1;
pWInfo->nLevel = nTabList;
pWInfo->pParse = pParse;
pWInfo->pTabList = pTabList;
@@ -6022,8 +6043,13 @@ WhereInfo *sqlite3WhereBegin(
#endif
if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0
&& (wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0 ){
int op = pWInfo->okOnePass ? OP_OpenWrite : OP_OpenRead;
int op = OP_OpenRead;
if( pWInfo->okOnePass ){
op = OP_OpenWrite;
pWInfo->aiCurOnePass[0] = pTabItem->iCursor;
};
sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
assert( pTabItem->iCursor==pLevel->iTabCur );
testcase( !pWInfo->okOnePass && pTab->nCol==BMS-1 );
testcase( !pWInfo->okOnePass && pTab->nCol==BMS );
if( !pWInfo->okOnePass && pTab->nCol<BMS && HasRowid(pTab) ){
@@ -6039,11 +6065,27 @@ WhereInfo *sqlite3WhereBegin(
}
if( pLoop->wsFlags & WHERE_INDEXED ){
Index *pIx = pLoop->u.btree.pIndex;
/* FIXME: As an optimization use pTabItem->iCursor if WHERE_IDX_ONLY */
int iIndexCur = pLevel->iIdxCur = iIdxCur ? iIdxCur : pParse->nTab++;
int iIndexCur;
int op = OP_OpenRead;
if( pWInfo->okOnePass && iIdxCur ){
Index *pJ = pTabItem->pTab->pIndex;
iIndexCur = iIdxCur;
assert( wctrlFlags & WHERE_ONEPASS_DESIRED );
while( ALWAYS(pJ) && pJ!=pIx ){
iIndexCur++;
pJ = pJ->pNext;
}
op = OP_OpenWrite;
pWInfo->aiCurOnePass[1] = iIndexCur;
}else if( iIdxCur && (wctrlFlags & WHERE_ONETABLE_ONLY)!=0 ){
iIndexCur = iIdxCur;
}else{
iIndexCur = pParse->nTab++;
}
pLevel->iIdxCur = iIndexCur;
assert( pIx->pSchema==pTab->pSchema );
assert( iIndexCur>=0 );
sqlite3VdbeAddOp3(v, OP_OpenRead, iIndexCur, pIx->tnum, iDb);
sqlite3VdbeAddOp3(v, op, iIndexCur, pIx->tnum, iDb);
sqlite3VdbeSetP4KeyInfo(pParse, pIx);
VdbeComment((v, "%s", pIx->zName));
}
@@ -6139,6 +6181,8 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
}
sqlite3VdbeJumpHere(v, addr);
}
VdbeNoopComment((v, "End WHERE-Loop %d: %s", i,
pWInfo->pTabList->a[pLevel->iFrom].pTab->zName));
}
/* The "break" point is here, just past the end of the outer loop.
@@ -6146,8 +6190,6 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
*/
sqlite3VdbeResolveLabel(v, pWInfo->iBreak);
/* Close all of the cursors that were opened by sqlite3WhereBegin.
*/
assert( pWInfo->nLevel<=pTabList->nSrc );
for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){
Index *pIdx = 0;
@@ -6155,6 +6197,12 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
Table *pTab = pTabItem->pTab;
assert( pTab!=0 );
pLoop = pLevel->pWLoop;
/* Close all of the cursors that were opened by sqlite3WhereBegin.
** Except, do not close cursors that will be reused by the OR optimization
** (WHERE_OMIT_OPEN_CLOSE). And do not close the OP_OpenWrite cursors
** created for the ONEPASS optimization.
*/
if( (pTab->tabFlags & TF_Ephemeral)==0
&& pTab->pSelect==0
&& (pWInfo->wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0
@@ -6163,7 +6211,10 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){
sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
}
if( (ws & WHERE_INDEXED)!=0 && (ws & (WHERE_IPK|WHERE_AUTO_INDEX))==0 ){
if( (ws & WHERE_INDEXED)!=0
&& (ws & (WHERE_IPK|WHERE_AUTO_INDEX))==0
&& pLevel->iIdxCur!=pWInfo->aiCurOnePass[1]
){
sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
}
}