diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/sqliteInt.h | 1 | ||||
-rw-r--r-- | src/test1.c | 1 | ||||
-rw-r--r-- | src/where.c | 108 | ||||
-rw-r--r-- | src/whereInt.h | 4 |
4 files changed, 111 insertions, 3 deletions
diff --git a/src/sqliteInt.h b/src/sqliteInt.h index dca5bb150..ebd0f01b2 100644 --- a/src/sqliteInt.h +++ b/src/sqliteInt.h @@ -1927,6 +1927,7 @@ struct sqlite3 { #define SQLITE_Coroutines 0x02000000 /* Co-routines for subqueries */ #define SQLITE_NullUnusedCols 0x04000000 /* NULL unused columns in subqueries */ #define SQLITE_OnePass 0x08000000 /* Single-pass DELETE and UPDATE */ +#define SQLITE_OrderBySubq 0x10000000 /* ORDER BY in subquery helps outer */ #define SQLITE_AllOpts 0xffffffff /* All optimizations */ /* diff --git a/src/test1.c b/src/test1.c index 9def739f4..177091a0e 100644 --- a/src/test1.c +++ b/src/test1.c @@ -8100,6 +8100,7 @@ static int SQLITE_TCLAPI optimization_control( { "distinct-opt", SQLITE_DistinctOpt }, { "cover-idx-scan", SQLITE_CoverIdxScan }, { "order-by-idx-join", SQLITE_OrderByIdxJoin }, + { "order-by-subquery", SQLITE_OrderBySubq }, { "transitive", SQLITE_Transitive }, { "omit-noop-join", SQLITE_OmitNoopJoin }, { "stat4", SQLITE_Stat4 }, diff --git a/src/where.c b/src/where.c index 98e9f117f..631b7581f 100644 --- a/src/where.c +++ b/src/where.c @@ -4010,6 +4010,10 @@ static int whereLoopAddBtree( #endif ApplyCostMultiplier(pNew->rRun, pTab->costMult); whereLoopOutputAdjust(pWC, pNew, rSize); + if( pSrc->pSelect ){ + if( pSrc->fg.viaCoroutine ) pNew->wsFlags |= WHERE_COROUTINE; + pNew->u.btree.pOrderBy = pSrc->pSelect->pOrderBy; + } rc = whereLoopInsert(pBuilder, pNew); pNew->nOut = rSize; if( rc ) break; @@ -4843,6 +4847,97 @@ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){ return rc; } +/* Implementation of the order-by-subquery optimization: +** +** WhereLoop pLoop, which the iLoop-th term of the nested loop, is really +** a subquery or CTE that has an ORDER BY clause. See if any of the terms +** in the subquery ORDER BY clause will satisfy pOrderBy from the outer +** query. Mark off all satisfied terms (by setting bits in *pOBSat) and +** return TRUE if they do. If not, return false. +** +** Example: +** +** CREATE TABLE t1(a,b,c, PRIMARY KEY(a,b)); +** CREATE TABLE t2(x,y); +** WITH t3(p,q) AS MATERIALIZED (SELECT x+y, x-y FROM t2 ORDER BY x+y) +** SELECT * FROM t3 JOIN t1 ON a=q ORDER BY p, b; +** +** The CTE named "t3" comes out in the natural order of "p", so the first +** first them of "ORDER BY p,b" is satisfied by a sequential scan of "t3" +** and sorting only needs to occur on the second term "b". +** +** Limitations: +** +** (1) The optimization is not applied if the outer ORDER BY contains +** a COLLATE clause. The optimization might be applied if the +** outer ORDER BY uses NULLS FIRST, NULLS LAST, ASC, and/or DESC as +** long as the subquery ORDER BY does the same. But if the +** outer ORDER BY uses COLLATE, even a redundant COLLATE, the +** optimization is bypassed. +** +** (2) The subquery ORDER BY terms must exactly match subquery result +** columns, including any COLLATE annotations. This routine relies +** on iOrderByCol to do matching between order by terms and result +** columns, and iOrderByCol will not be set if the result column +** and ORDER BY collations differ. +** +** (3) The subquery and outer ORDER BY can be in opposite directions as +** long as the subquery is materialized. If the subquery is +** implemented as a co-routine, the sort orders must be in the same +** direction because there is no way to run a co-routine backwards. +*/ +static SQLITE_NOINLINE int wherePathMatchSubqueryOB( + WhereInfo *pWInfo, /* The WHERE clause */ + WhereLoop *pLoop, /* The nested loop term that is a subquery */ + int iLoop, /* Which level of the nested loop. 0==outermost */ + int iCur, /* Cursor used by the this loop */ + ExprList *pOrderBy, /* The ORDER BY clause on the whole query */ + Bitmask *pRevMask, /* When loops need to go in reverse order */ + Bitmask *pOBSat /* Which terms of pOrderBy are satisfied so far */ +){ + int iOB; /* Index into pOrderBy->a[] */ + int jSub; /* Index into pSubOB->a[] */ + u8 rev = 0; /* True if iOB and jSub sort in opposite directions */ + u8 revIdx = 0; /* Sort direction for jSub */ + Expr *pOBExpr; /* Current term of outer ORDER BY */ + ExprList *pSubOB; /* Complete ORDER BY on the subquery */ + + pSubOB = pLoop->u.btree.pOrderBy; + assert( pSubOB!=0 ); + for(iOB=0; (MASKBIT(iOB) & *pOBSat)!=0; iOB++){} + for(jSub=0; jSub<pSubOB->nExpr && iOB<pOrderBy->nExpr; jSub++, iOB++){ + if( pSubOB->a[jSub].u.x.iOrderByCol==0 ) break; + pOBExpr = pOrderBy->a[iOB].pExpr; + if( pOBExpr->op!=TK_COLUMN && pOBExpr->op!=TK_AGG_COLUMN ) break; + if( pOBExpr->iTable!=iCur ) break; + if( pOBExpr->iColumn!=pSubOB->a[jSub].u.x.iOrderByCol-1 ) break; + if( (pWInfo->wctrlFlags & WHERE_GROUPBY)==0 ){ + u8 sfOB = pOrderBy->a[iOB].fg.sortFlags; /* sortFlags for iOB */ + u8 sfSub = pSubOB->a[jSub].fg.sortFlags; /* sortFlags for jSub */ + if( (sfSub & KEYINFO_ORDER_BIGNULL) != (sfOB & KEYINFO_ORDER_BIGNULL) ){ + break; + } + revIdx = sfSub & KEYINFO_ORDER_DESC; + if( jSub>0 ){ + if( (rev^revIdx)!=(sfOB & KEYINFO_ORDER_DESC) ){ + break; + } + }else{ + rev = revIdx ^ (sfOB & KEYINFO_ORDER_DESC); + if( rev ){ + if( (pLoop->wsFlags & WHERE_COROUTINE)!=0 ){ + /* Cannot run a co-routine in reverse order */ + break; + } + *pRevMask |= MASKBIT(iLoop); + } + } + } + *pOBSat |= MASKBIT(iOB); + } + return jSub>0; +} + /* ** Examine a WherePath (with the addition of the extra WhereLoop of the 6th ** parameters) to see if it outputs rows in the requested ORDER BY @@ -4988,9 +5083,18 @@ static i8 wherePathSatisfiesOrderBy( if( (pLoop->wsFlags & WHERE_ONEROW)==0 ){ if( pLoop->wsFlags & WHERE_IPK ){ + if( pLoop->u.btree.pOrderBy + && OptimizationEnabled(db, SQLITE_OrderBySubq) + && wherePathMatchSubqueryOB(pWInfo,pLoop,iLoop,iCur, + pOrderBy,pRevMask, &obSat) + ){ + nColumn = 0; + isOrderDistinct = 0; + }else{ + nColumn = 1; + } pIndex = 0; nKeyCol = 0; - nColumn = 1; }else if( (pIndex = pLoop->u.btree.pIndex)==0 || pIndex->bUnordered ){ return 0; }else{ @@ -5085,7 +5189,7 @@ static i8 wherePathSatisfiesOrderBy( } /* Find the ORDER BY term that corresponds to the j-th column - ** of the index and mark that ORDER BY term off + ** of the index and mark that ORDER BY term having been satisfied. */ isMatch = 0; for(i=0; bOnce && i<nOrderBy; i++){ diff --git a/src/whereInt.h b/src/whereInt.h index d3226e086..c9afed267 100644 --- a/src/whereInt.h +++ b/src/whereInt.h @@ -143,6 +143,7 @@ struct WhereLoop { u16 nTop; /* Size of TOP vector */ u16 nDistinctCol; /* Index columns used to sort for DISTINCT */ Index *pIndex; /* Index used, or NULL */ + ExprList *pOrderBy; /* ORDER BY clause if this is really a subquery */ } btree; struct { /* Information for virtual tables */ int idxNum; /* Index number */ @@ -636,7 +637,8 @@ void sqlite3WhereTabFuncArgs(Parse*, SrcItem*, WhereClause*); #define WHERE_BLOOMFILTER 0x00400000 /* Consider using a Bloom-filter */ #define WHERE_SELFCULL 0x00800000 /* nOut reduced by extra WHERE terms */ #define WHERE_OMIT_OFFSET 0x01000000 /* Set offset counter to zero */ - /* 0x02000000 -- available for reuse */ +#define WHERE_COROUTINE 0x02000000 /* Implemented by co-routine. + ** NB: False-negatives are possible */ #define WHERE_EXPRIDX 0x04000000 /* Uses an index-on-expressions */ #endif /* !defined(SQLITE_WHEREINT_H) */ |