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Overview
Comment: | Appears to work now. Needs test cases, more comments, and code optimization. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | orderby-limit |
Files: | files | file ages | folders |
SHA1: |
990fe50c9182f74c9b54a12602c4c30d |
User & Date: | drh 2016-05-19 22:40:04.862 |
Context
2016-05-20
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00:21 | A few simple test cases for the ORDER BY LIMIT optimization. (check-in: 08849eab0f user: drh tags: orderby-limit) | |
2016-05-19
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22:40 | Appears to work now. Needs test cases, more comments, and code optimization. (check-in: 990fe50c91 user: drh tags: orderby-limit) | |
22:13 | In a query with both ORDER BY and LIMIT, if the inner loop satisfies the ORDER BY then try to cut short each invocation of the inner loop once the LIMIT has been satisfied. This check-in is a partial implementation only. (check-in: 852d1eda6e user: drh tags: orderby-limit) | |
Changes
Changes to src/sqliteInt.h.
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2536 2537 2538 2539 2540 2541 2542 | #define WHERE_OR_SUBCLAUSE 0x0020 /* Processing a sub-WHERE as part of ** the OR optimization */ #define WHERE_GROUPBY 0x0040 /* pOrderBy is really a GROUP BY */ #define WHERE_DISTINCTBY 0x0080 /* pOrderby is really a DISTINCT clause */ #define WHERE_WANT_DISTINCT 0x0100 /* All output needs to be distinct */ #define WHERE_SORTBYGROUP 0x0200 /* Support sqlite3WhereIsSorted() */ #define WHERE_SEEK_TABLE 0x0400 /* Do not defer seeks on main table */ | | | 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 | #define WHERE_OR_SUBCLAUSE 0x0020 /* Processing a sub-WHERE as part of ** the OR optimization */ #define WHERE_GROUPBY 0x0040 /* pOrderBy is really a GROUP BY */ #define WHERE_DISTINCTBY 0x0080 /* pOrderby is really a DISTINCT clause */ #define WHERE_WANT_DISTINCT 0x0100 /* All output needs to be distinct */ #define WHERE_SORTBYGROUP 0x0200 /* Support sqlite3WhereIsSorted() */ #define WHERE_SEEK_TABLE 0x0400 /* Do not defer seeks on main table */ #define WHERE_ORDERBY_LIMIT 0x0800 /* ORDERBY+LIMIT on the inner loop */ /* 0x1000 not currently used */ /* 0x2000 not currently used */ #define WHERE_USE_LIMIT 0x4000 /* Use the LIMIT in cost estimates */ /* 0x8000 not currently used */ /* Allowed return values from sqlite3WhereIsDistinct() */ |
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Changes to src/where.c.
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3258 3259 3260 3261 3262 3263 3264 | ** the pOrderBy terms can be matched in any order. With ORDER BY, the ** pOrderBy terms must be matched in strict left-to-right order. */ static i8 wherePathSatisfiesOrderBy( WhereInfo *pWInfo, /* The WHERE clause */ ExprList *pOrderBy, /* ORDER BY or GROUP BY or DISTINCT clause to check */ WherePath *pPath, /* The WherePath to check */ | | > | 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 | ** the pOrderBy terms can be matched in any order. With ORDER BY, the ** pOrderBy terms must be matched in strict left-to-right order. */ static i8 wherePathSatisfiesOrderBy( WhereInfo *pWInfo, /* The WHERE clause */ ExprList *pOrderBy, /* ORDER BY or GROUP BY or DISTINCT clause to check */ WherePath *pPath, /* The WherePath to check */ u16 wctrlFlags, /* WHERE_GROUPBY or _DISTINCTBY or _ORDERBY_LIMIT */ u16 nLoop, /* Number of entries in pPath->aLoop[] */ WhereLoop *pLast, /* Add this WhereLoop to the end of pPath->aLoop[] */ Bitmask *pRevMask /* OUT: Mask of WhereLoops to run in reverse order */ ){ u8 revSet; /* True if rev is known */ u8 rev; /* Composite sort order */ u8 revIdx; /* Index sort order */ u8 isOrderDistinct; /* All prior WhereLoops are order-distinct */ u8 distinctColumns; /* True if the loop has UNIQUE NOT NULL columns */ u8 isMatch; /* iColumn matches a term of the ORDER BY clause */ u16 eqOpMask; /* Allowed equality operators */ u16 nKeyCol; /* Number of key columns in pIndex */ u16 nColumn; /* Total number of ordered columns in the index */ u16 nOrderBy; /* Number terms in the ORDER BY clause */ int iLoop; /* Index of WhereLoop in pPath being processed */ int i, j; /* Loop counters */ int iCur; /* Cursor number for current WhereLoop */ int iColumn; /* A column number within table iCur */ |
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3319 3320 3321 3322 3323 3324 3325 3326 3327 | nOrderBy = pOrderBy->nExpr; testcase( nOrderBy==BMS-1 ); if( nOrderBy>BMS-1 ) return 0; /* Cannot optimize overly large ORDER BYs */ isOrderDistinct = 1; obDone = MASKBIT(nOrderBy)-1; orderDistinctMask = 0; ready = 0; for(iLoop=0; isOrderDistinct && obSat<obDone && iLoop<=nLoop; iLoop++){ if( iLoop>0 ) ready |= pLoop->maskSelf; | > > > | > > > > | | 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 | nOrderBy = pOrderBy->nExpr; testcase( nOrderBy==BMS-1 ); if( nOrderBy>BMS-1 ) return 0; /* Cannot optimize overly large ORDER BYs */ isOrderDistinct = 1; obDone = MASKBIT(nOrderBy)-1; orderDistinctMask = 0; ready = 0; eqOpMask = WO_EQ | WO_IS | WO_ISNULL; if( wctrlFlags & WHERE_ORDERBY_LIMIT ) eqOpMask |= WO_IN; for(iLoop=0; isOrderDistinct && obSat<obDone && iLoop<=nLoop; iLoop++){ if( iLoop>0 ) ready |= pLoop->maskSelf; if( iLoop<nLoop ){ pLoop = pPath->aLoop[iLoop]; if( wctrlFlags & WHERE_ORDERBY_LIMIT ) continue; }else{ pLoop = pLast; } if( pLoop->wsFlags & WHERE_VIRTUALTABLE ){ if( pLoop->u.vtab.isOrdered ) obSat = obDone; break; } iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor; /* Mark off any ORDER BY term X that is a column in the table of ** the current loop for which there is term in the WHERE ** clause of the form X IS NULL or X=? that reference only outer ** loops. */ for(i=0; i<nOrderBy; i++){ if( MASKBIT(i) & obSat ) continue; pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr); if( pOBExpr->op!=TK_COLUMN ) continue; if( pOBExpr->iTable!=iCur ) continue; pTerm = sqlite3WhereFindTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn, ~ready, eqOpMask, 0); if( pTerm==0 ) continue; if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){ const char *z1, *z2; pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr); if( !pColl ) pColl = db->pDfltColl; z1 = pColl->zName; pColl = sqlite3ExprCollSeq(pWInfo->pParse, pTerm->pExpr); |
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3379 3380 3381 3382 3383 3384 3385 | ** that are not constrained by == or IN. */ rev = revSet = 0; distinctColumns = 0; for(j=0; j<nColumn; j++){ u8 bOnce; /* True to run the ORDER BY search loop */ | | > > | | 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401 3402 3403 3404 3405 3406 | ** that are not constrained by == or IN. */ rev = revSet = 0; distinctColumns = 0; for(j=0; j<nColumn; j++){ u8 bOnce; /* True to run the ORDER BY search loop */ /* Skip over == and IS and ISNULL terms. ** (Also skip IN terms when doing WHERE_ORDERBY_LIMIT processing) */ if( j<pLoop->u.btree.nEq && pLoop->nSkip==0 && ((i = pLoop->aLTerm[j]->eOperator) & eqOpMask)!=0 ){ if( i & WO_ISNULL ){ testcase( isOrderDistinct ); isOrderDistinct = 0; } continue; } |
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3909 3910 3911 3912 3913 3914 3915 3916 3917 3918 3919 3920 3921 3922 | pWInfo->eDistinct = WHERE_DISTINCT_ORDERED; } }else{ pWInfo->nOBSat = pFrom->isOrdered; pWInfo->revMask = pFrom->revLoop; if( pWInfo->nOBSat<=0 ){ pWInfo->nOBSat = 0; } } if( (pWInfo->wctrlFlags & WHERE_SORTBYGROUP) && pWInfo->nOBSat==pWInfo->pOrderBy->nExpr && nLoop>0 ){ Bitmask revMask = 0; int nOrder = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, | > > > > > > > > > | 3919 3920 3921 3922 3923 3924 3925 3926 3927 3928 3929 3930 3931 3932 3933 3934 3935 3936 3937 3938 3939 3940 3941 | pWInfo->eDistinct = WHERE_DISTINCT_ORDERED; } }else{ pWInfo->nOBSat = pFrom->isOrdered; pWInfo->revMask = pFrom->revLoop; if( pWInfo->nOBSat<=0 ){ pWInfo->nOBSat = 0; if( nLoop>0 ){ Bitmask m; int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, pFrom, WHERE_ORDERBY_LIMIT, nLoop-1, pFrom->aLoop[nLoop-1], &m); if( rc==pWInfo->pOrderBy->nExpr ){ pWInfo->bOrderedInnerLoop = 1; pWInfo->revMask = m; } } } } if( (pWInfo->wctrlFlags & WHERE_SORTBYGROUP) && pWInfo->nOBSat==pWInfo->pOrderBy->nExpr && nLoop>0 ){ Bitmask revMask = 0; int nOrder = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, |
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