Many hyperlinks are disabled.
Use anonymous login
to enable hyperlinks.
Overview
Comment: | Change the internal sqlite3WhereBegin() to report that the ORDER BY clause is satisfied by indices using the WhereInfo.nOBSat field of the returned structure. |
---|---|
Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
22989f3588531efd555cc29d6c576e7a |
User & Date: | drh 2012-09-24 15:30:54.533 |
Context
2012-09-24
| ||
19:50 | Remove an unused subfunction parameter and an obsolete comment from the query planner logic in where.c. (check-in: 349a55cd8b user: drh tags: trunk) | |
15:30 | Change the internal sqlite3WhereBegin() to report that the ORDER BY clause is satisfied by indices using the WhereInfo.nOBSat field of the returned structure. (check-in: 22989f3588 user: drh tags: trunk) | |
11:43 | Update documentation to describe the threadsafety of sqlite3_enable_shared_cache(). (check-in: e081890cd7 user: drh tags: trunk) | |
Changes
Changes to src/select.c.
︙ | ︙ | |||
4094 4095 4096 4097 4098 4099 4100 | } if( !isAgg && pGroupBy==0 ){ /* No aggregate functions and no GROUP BY clause */ ExprList *pDist = (sDistinct.isTnct ? p->pEList : 0); /* Begin the database scan. */ | | > | 4094 4095 4096 4097 4098 4099 4100 4101 4102 4103 4104 4105 4106 4107 4108 4109 4110 4111 4112 | } if( !isAgg && pGroupBy==0 ){ /* No aggregate functions and no GROUP BY clause */ ExprList *pDist = (sDistinct.isTnct ? p->pEList : 0); /* Begin the database scan. */ pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pOrderBy, pDist, 0,0); if( pWInfo==0 ) goto select_end; if( pWInfo->nRowOut < p->nSelectRow ) p->nSelectRow = pWInfo->nRowOut; if( pWInfo->eDistinct ) sDistinct.eTnctType = pWInfo->eDistinct; if( pOrderBy && pWInfo->nOBSat==pOrderBy->nExpr ) pOrderBy = 0; /* If sorting index that was created by a prior OP_OpenEphemeral ** instruction ended up not being needed, then change the OP_OpenEphemeral ** into an OP_Noop. */ if( addrSortIndex>=0 && pOrderBy==0 ){ sqlite3VdbeChangeToNoop(v, addrSortIndex); |
︙ | ︙ | |||
4225 4226 4227 4228 4229 4230 4231 | /* Begin a loop that will extract all source rows in GROUP BY order. ** This might involve two separate loops with an OP_Sort in between, or ** it might be a single loop that uses an index to extract information ** in the right order to begin with. */ sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset); | | | < | 4226 4227 4228 4229 4230 4231 4232 4233 4234 4235 4236 4237 4238 4239 4240 4241 4242 4243 4244 4245 4246 | /* Begin a loop that will extract all source rows in GROUP BY order. ** This might involve two separate loops with an OP_Sort in between, or ** it might be a single loop that uses an index to extract information ** in the right order to begin with. */ sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset); pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pGroupBy, 0, 0, 0); if( pWInfo==0 ) goto select_end; if( pWInfo->nOBSat==pGroupBy->nExpr ){ /* The optimizer is able to deliver rows in group by order so ** we do not have to sort. The OP_OpenEphemeral table will be ** cancelled later because we still need to use the pKeyInfo */ groupBySort = 0; }else{ /* Rows are coming out in undetermined order. We have to push ** each row into a sorting index, terminate the first loop, ** then loop over the sorting index in order to get the output ** in sorted order */ |
︙ | ︙ | |||
4482 4483 4484 4485 4486 4487 4488 4489 4490 4491 4492 4493 4494 4495 4496 4497 4498 4499 4500 4501 | ** satisfying the 'ORDER BY' clause than it does in other cases. ** Refer to code and comments in where.c for details. */ ExprList *pMinMax = 0; u8 flag = minMaxQuery(p); if( flag ){ assert( !ExprHasProperty(p->pEList->a[0].pExpr, EP_xIsSelect) ); pMinMax = sqlite3ExprListDup(db, p->pEList->a[0].pExpr->x.pList,0); pDel = pMinMax; if( pMinMax && !db->mallocFailed ){ pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN ?1:0; pMinMax->a[0].pExpr->op = TK_COLUMN; } } /* This case runs if the aggregate has no GROUP BY clause. The ** processing is much simpler since there is only a single row ** of output. */ resetAccumulator(pParse, &sAggInfo); | > | | | 4482 4483 4484 4485 4486 4487 4488 4489 4490 4491 4492 4493 4494 4495 4496 4497 4498 4499 4500 4501 4502 4503 4504 4505 4506 4507 4508 4509 4510 4511 4512 4513 4514 4515 4516 | ** satisfying the 'ORDER BY' clause than it does in other cases. ** Refer to code and comments in where.c for details. */ ExprList *pMinMax = 0; u8 flag = minMaxQuery(p); if( flag ){ assert( !ExprHasProperty(p->pEList->a[0].pExpr, EP_xIsSelect) ); assert( p->pEList->a[0].pExpr->x.pList->nExpr==1 ); pMinMax = sqlite3ExprListDup(db, p->pEList->a[0].pExpr->x.pList,0); pDel = pMinMax; if( pMinMax && !db->mallocFailed ){ pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN ?1:0; pMinMax->a[0].pExpr->op = TK_COLUMN; } } /* This case runs if the aggregate has no GROUP BY clause. The ** processing is much simpler since there is only a single row ** of output. */ resetAccumulator(pParse, &sAggInfo); pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMax,0,flag,0); if( pWInfo==0 ){ sqlite3ExprListDelete(db, pDel); goto select_end; } updateAccumulator(pParse, &sAggInfo); if( pWInfo->nOBSat>0 ){ sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak); VdbeComment((v, "%s() by index", (flag==WHERE_ORDERBY_MIN?"min":"max"))); } sqlite3WhereEnd(pWInfo); finalizeAggFunctions(pParse, &sAggInfo); } |
︙ | ︙ |
Changes to src/sqliteInt.h.
︙ | ︙ | |||
1979 1980 1981 1982 1983 1984 1985 1986 | ** first part does the start of the WHERE loop and the second ** half does the tail of the WHERE loop. An instance of ** this structure is returned by the first half and passed ** into the second half to give some continuity. */ struct WhereInfo { Parse *pParse; /* Parsing and code generating context */ u16 wctrlFlags; /* Flags originally passed to sqlite3WhereBegin() */ | > > | < | 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 | ** first part does the start of the WHERE loop and the second ** half does the tail of the WHERE loop. An instance of ** this structure is returned by the first half and passed ** into the second half to give some continuity. */ struct WhereInfo { Parse *pParse; /* Parsing and code generating context */ SrcList *pTabList; /* List of tables in the join */ u16 nOBSat; /* Number of ORDER BY terms satisfied by indices */ u16 wctrlFlags; /* Flags originally passed to sqlite3WhereBegin() */ u8 okOnePass; /* Ok to use one-pass algorithm for UPDATE/DELETE */ u8 untestedTerms; /* Not all WHERE terms resolved by outer loop */ u8 eDistinct; /* One of the WHERE_DISTINCT_* values below */ int iTop; /* The very beginning of the WHERE loop */ int iContinue; /* Jump here to continue with next record */ int iBreak; /* Jump here to break out of the loop */ int nLevel; /* Number of nested loop */ struct WhereClause *pWC; /* Decomposition of the WHERE clause */ double savedNQueryLoop; /* pParse->nQueryLoop outside the WHERE loop */ double nRowOut; /* Estimated number of output rows */ |
︙ | ︙ | |||
2807 2808 2809 2810 2811 2812 2813 | int sqlite3IsReadOnly(Parse*, Table*, int); void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int); #if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY) Expr *sqlite3LimitWhere(Parse *, SrcList *, Expr *, ExprList *, Expr *, Expr *, char *); #endif void sqlite3DeleteFrom(Parse*, SrcList*, Expr*); void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int); | | < | 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 | int sqlite3IsReadOnly(Parse*, Table*, int); void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int); #if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY) Expr *sqlite3LimitWhere(Parse *, SrcList *, Expr *, ExprList *, Expr *, Expr *, char *); #endif void sqlite3DeleteFrom(Parse*, SrcList*, Expr*); void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int); WhereInfo *sqlite3WhereBegin(Parse*,SrcList*,Expr*,ExprList*,ExprList*,u16,int); void sqlite3WhereEnd(WhereInfo*); int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int, u8); void sqlite3ExprCodeGetColumnOfTable(Vdbe*, Table*, int, int, int); void sqlite3ExprCodeMove(Parse*, int, int, int); void sqlite3ExprCacheStore(Parse*, int, int, int); void sqlite3ExprCachePush(Parse*); void sqlite3ExprCachePop(Parse*, int); |
︙ | ︙ |
Changes to src/where.c.
︙ | ︙ | |||
4663 4664 4665 4666 4667 4668 4669 | ** move the row2 cursor to a null row ** goto start ** fi ** end ** ** ORDER BY CLAUSE PROCESSING ** | | | | | | | | | 4663 4664 4665 4666 4667 4668 4669 4670 4671 4672 4673 4674 4675 4676 4677 4678 4679 4680 4681 4682 4683 4684 4685 4686 4687 4688 4689 4690 4691 4692 4693 4694 | ** move the row2 cursor to a null row ** goto start ** fi ** end ** ** ORDER BY CLAUSE PROCESSING ** ** pOrderBy 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 pOrderBy 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 ** the returned WhereInfo.nOBSat field is set to pOrderBy->nExpr. 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 WhereInfo.nOBSat is 0. */ WhereInfo *sqlite3WhereBegin( Parse *pParse, /* The parser context */ SrcList *pTabList, /* A list of all tables to be scanned */ Expr *pWhere, /* The WHERE clause */ ExprList *pOrderBy, /* An ORDER BY clause, or NULL */ ExprList *pDistinct, /* The select-list for DISTINCT queries - or NULL */ u16 wctrlFlags, /* One of the WHERE_* flags defined in sqliteInt.h */ int iIdxCur /* If WHERE_ONETABLE_ONLY is set, index cursor number */ ){ int i; /* Loop counter */ int nByteWInfo; /* Num. bytes allocated for WhereInfo struct */ int nTabList; /* Number of elements in pTabList */ |
︙ | ︙ | |||
4905 4906 4907 4908 4909 4910 4911 | nUnconstrained = 0; notIndexed = 0; for(isOptimal=(iFrom<nTabList-1); isOptimal>=0 && bestJ<0; isOptimal--){ Bitmask mask; /* Mask of tables not yet ready */ for(j=iFrom, pTabItem=&pTabList->a[j]; j<nTabList; j++, pTabItem++){ int doNotReorder; /* True if this table should not be reordered */ WhereCost sCost; /* Cost information from best[Virtual]Index() */ | | | | | | 4905 4906 4907 4908 4909 4910 4911 4912 4913 4914 4915 4916 4917 4918 4919 4920 4921 4922 4923 4924 4925 4926 4927 4928 4929 4930 4931 4932 4933 4934 4935 4936 4937 4938 4939 4940 4941 4942 4943 4944 4945 | nUnconstrained = 0; notIndexed = 0; for(isOptimal=(iFrom<nTabList-1); isOptimal>=0 && bestJ<0; isOptimal--){ Bitmask mask; /* Mask of tables not yet ready */ for(j=iFrom, pTabItem=&pTabList->a[j]; j<nTabList; j++, pTabItem++){ int doNotReorder; /* True if this table should not be reordered */ WhereCost sCost; /* Cost information from best[Virtual]Index() */ ExprList *pOB; /* ORDER BY clause for index to optimize */ ExprList *pDist; /* DISTINCT clause for index to optimize */ doNotReorder = (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0; if( j!=iFrom && doNotReorder ) break; m = getMask(pMaskSet, pTabItem->iCursor); if( (m & notReady)==0 ){ if( j==iFrom ) iFrom++; continue; } mask = (isOptimal ? m : notReady); pOB = (i==0) ? pOrderBy : 0; pDist = (i==0 ? pDistinct : 0); if( pTabItem->pIndex==0 ) nUnconstrained++; WHERETRACE(("=== trying table %d with isOptimal=%d ===\n", j, isOptimal)); assert( pTabItem->pTab ); #ifndef SQLITE_OMIT_VIRTUALTABLE if( IsVirtual(pTabItem->pTab) ){ sqlite3_index_info **pp = &pWInfo->a[j].pIdxInfo; bestVirtualIndex(pParse, pWC, pTabItem, mask, notReady, pOB, &sCost, pp); }else #endif { bestBtreeIndex(pParse, pWC, pTabItem, mask, notReady, pOB, pDist, &sCost); } assert( isOptimal || (sCost.used¬Ready)==0 ); /* If an INDEXED BY clause is present, then the plan must use that ** index if it uses any index at all */ assert( pTabItem->pIndex==0 |
︙ | ︙ | |||
4991 4992 4993 4994 4995 4996 4997 | } assert( bestJ>=0 ); assert( notReady & getMask(pMaskSet, pTabList->a[bestJ].iCursor) ); WHERETRACE(("*** Optimizer selects table %d for loop %d" " with cost=%g and nRow=%g\n", bestJ, pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow)); /* The ALWAYS() that follows was added to hush up clang scan-build */ | | | | 4991 4992 4993 4994 4995 4996 4997 4998 4999 5000 5001 5002 5003 5004 5005 5006 | } assert( bestJ>=0 ); assert( notReady & getMask(pMaskSet, pTabList->a[bestJ].iCursor) ); WHERETRACE(("*** Optimizer selects table %d for loop %d" " with cost=%g and nRow=%g\n", bestJ, pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow)); /* The ALWAYS() that follows was added to hush up clang scan-build */ 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; } andFlags &= bestPlan.plan.wsFlags; pLevel->plan = bestPlan.plan; |
︙ | ︙ | |||
5045 5046 5047 5048 5049 5050 5051 | if( pParse->nErr || db->mallocFailed ){ goto whereBeginError; } /* If the total query only selects a single row, then the ORDER BY ** clause is irrelevant. */ | | | | 5045 5046 5047 5048 5049 5050 5051 5052 5053 5054 5055 5056 5057 5058 5059 5060 | if( pParse->nErr || db->mallocFailed ){ goto whereBeginError; } /* If the total query only selects a single row, then the ORDER BY ** clause is irrelevant. */ if( (andFlags & WHERE_UNIQUE)!=0 && pOrderBy ){ pWInfo->nOBSat = pOrderBy->nExpr; } /* If the caller is an UPDATE or DELETE statement that is requesting ** to use a one-pass algorithm, determine if this is appropriate. ** The one-pass algorithm only works if the WHERE clause constraints ** the statement to update a single row. */ |
︙ | ︙ |