From 8c6f666b26cd8244da3d7fb6da478b43105bc679 Mon Sep 17 00:00:00 2001 From: drh Date: Mon, 26 Apr 2010 19:17:26 +0000 Subject: [PATCH] Optimization: Convert an ORDER BY clause into a no-op if the query also contains a GROUP BY clause that will force the same output order. FossilOrigin-Name: ca9d86baf70f210d331ce93102177c8005c494cb --- manifest | 22 +++++++++++----------- manifest.uuid | 2 +- src/expr.c | 39 ++++++++++++++++++++++++++------------- src/select.c | 12 ++++++++++++ src/sqliteInt.h | 4 +++- 5 files changed, 53 insertions(+), 26 deletions(-) diff --git a/manifest b/manifest index 438c37caf5..f2bb25a6d4 100644 --- a/manifest +++ b/manifest @@ -1,8 +1,8 @@ -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 -C Change\sthe\sdefault_cache_size\spragma\sto\salways\sstore\sa\spositive\svalue. -D 2010-04-26T17:36:35 +C Optimization:\sConvert\san\sORDER\sBY\sclause\sinto\sa\sno-op\sif\sthe\squery\salso\ncontains\sa\sGROUP\sBY\sclause\sthat\swill\sforce\sthe\ssame\soutput\sorder. +D 2010-04-26T19:17:27 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0 F Makefile.in 4f2f967b7e58a35bb74fb7ec8ae90e0f4ca7868b F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654 @@ -121,7 +121,7 @@ F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac F src/ctime.c 51553a859994d01d8bf3500747f66a890c459774 F src/date.c 485a4409a384310e6d93fd1104a9d0a8658becd9 F src/delete.c 610dc008e88a9599f905f5cbe9577ac9c36e0581 -F src/expr.c 6baed2a0448d494233d9c0a610eea018ab386a32 +F src/expr.c 286f62b24217ade1c14ba56de413ffdd607b6a41 F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb F src/fkey.c e2116672a6bd610dc888e27df292ebc7999c9bb0 F src/func.c 0c28599430856631216b6c0131c51c89bf516026 @@ -167,11 +167,11 @@ F src/printf.c 5f5b65a83e63f2096a541a340722a509fa0240a7 F src/random.c cd4a67b3953b88019f8cd4ccd81394a8ddfaba50 F src/resolve.c ac5f1a713cd1ae77f08b83cc69581e11bf5ae6f9 F src/rowset.c 69afa95a97c524ba6faf3805e717b5b7ae85a697 -F src/select.c b7c9a40bc1567bceff52ad4b73108734ee4bf268 +F src/select.c c03d8a0565febcde8c6a12c5d77d065fddae889b F src/shell.c c40427c7245535a04a9cb4a417b6cc05c022e6a4 F src/sqlite.h.in dc98616304e3e776008655671d81e3ad3028ada7 F src/sqlite3ext.h 69dfb8116af51b84a029cddb3b35062354270c89 -F src/sqliteInt.h 15339730eeeb571ed515d125e3446ae80ec3b4ef +F src/sqliteInt.h 4303fdad2e96c56f510cc8e31a647b1b8c5a5254 F src/sqliteLimit.h 3afab2291762b5d09ae20c18feb8e9fa935a60a6 F src/status.c 4df6fe7dce2d256130b905847c6c60055882bdbe F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e @@ -801,14 +801,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f -P 245d934b72cbc6e897193e7892195b6561995939 -R 1a721a7e3d8403e75d36dd22925eaa62 +P 36fb2cae75b5dfe1fe818895f03c0b4f4190a722 +R 39601da2973f0d22788b2e5833832c44 U drh -Z d3141c0d53e4f0054b2b5670e084ebf2 +Z 9d6faae1537324b0ce24766e774d3c1e -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) -iD8DBQFL1c8noxKgR168RlERAk2fAJwIn4ScLPQ6cD+9QSCdisImYXuM8QCfTXNt -XvbQVdO+MSVbonYnIw7jvtU= -=Dgm7 +iD8DBQFL1ebKoxKgR168RlERAixaAJ9MtsB9+gfG3m3Uh9CtO8GjRZH+fgCghDsR +Xx+FaS5+UH9uAeCG9zc761s= +=CIW0 -----END PGP SIGNATURE----- diff --git a/manifest.uuid b/manifest.uuid index 736cbd9388..8feb63902d 100644 --- a/manifest.uuid +++ b/manifest.uuid @@ -1 +1 @@ -36fb2cae75b5dfe1fe818895f03c0b4f4190a722 \ No newline at end of file +ca9d86baf70f210d331ce93102177c8005c494cb \ No newline at end of file diff --git a/src/expr.c b/src/expr.c index 034088fafc..70526aea61 100644 --- a/src/expr.c +++ b/src/expr.c @@ -3440,7 +3440,6 @@ void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){ ** an incorrect 0 or 1 could lead to a malfunction. */ int sqlite3ExprCompare(Expr *pA, Expr *pB){ - int i; if( pA==0||pB==0 ){ return pB==pA ? 0 : 2; } @@ -3453,18 +3452,7 @@ int sqlite3ExprCompare(Expr *pA, Expr *pB){ if( pA->op!=pB->op ) return 2; if( sqlite3ExprCompare(pA->pLeft, pB->pLeft) ) return 2; if( sqlite3ExprCompare(pA->pRight, pB->pRight) ) return 2; - - if( pA->x.pList && pB->x.pList ){ - if( pA->x.pList->nExpr!=pB->x.pList->nExpr ) return 2; - for(i=0; ix.pList->nExpr; i++){ - Expr *pExprA = pA->x.pList->a[i].pExpr; - Expr *pExprB = pB->x.pList->a[i].pExpr; - if( sqlite3ExprCompare(pExprA, pExprB) ) return 2; - } - }else if( pA->x.pList || pB->x.pList ){ - return 2; - } - + if( sqlite3ExprListCompare(pA->x.pList, pB->x.pList) ) return 2; if( pA->iTable!=pB->iTable || pA->iColumn!=pB->iColumn ) return 2; if( ExprHasProperty(pA, EP_IntValue) ){ if( !ExprHasProperty(pB, EP_IntValue) || pA->u.iValue!=pB->u.iValue ){ @@ -3481,6 +3469,31 @@ int sqlite3ExprCompare(Expr *pA, Expr *pB){ return 0; } +/* +** Compare two ExprList objects. Return 0 if they are identical and +** non-zero if they differ in any way. +** +** This routine might return non-zero for equivalent ExprLists. The +** only consequence will be disabled optimizations. But this routine +** must never return 0 if the two ExprList objects are different, or +** a malfunction will result. +** +** Two NULL pointers are considered to be the same. But a NULL pointer +** always differs from a non-NULL pointer. +*/ +int sqlite3ExprListCompare(ExprList *pA, ExprList *pB){ + int i; + if( pA==0 && pB==0 ) return 0; + if( pA==0 || pB==0 ) return 1; + if( pA->nExpr!=pB->nExpr ) return 1; + for(i=0; inExpr; i++){ + Expr *pExprA = pA->a[i].pExpr; + Expr *pExprB = pB->a[i].pExpr; + if( pA->a[i].sortOrder!=pB->a[i].sortOrder ) return 1; + if( sqlite3ExprCompare(pExprA, pExprB) ) return 1; + } + return 0; +} /* ** Add a new element to the pAggInfo->aCol[] array. Return the index of diff --git a/src/select.c b/src/select.c index 47e409ffc8..9a016039a8 100644 --- a/src/select.c +++ b/src/select.c @@ -3718,6 +3718,18 @@ int sqlite3Select( isDistinct = 0; } + /* If there is both a GROUP BY and an ORDER BY clause and they are + ** identical, then disable the ORDER BY clause since the GROUP BY + ** will cause elements to come out in the correct order. This is + ** an optimization - the correct answer should result regardless. + ** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER + ** to disable this optimization for testing purposes. + */ + if( sqlite3ExprListCompare(p->pGroupBy, pOrderBy)==0 + && (db->flags & SQLITE_GroupByOrder)==0 ){ + pOrderBy = 0; + } + /* If there is an ORDER BY clause, then this sorting ** index might end up being unused if the data can be ** extracted in pre-sorted order. If that is the case, then the diff --git a/src/sqliteInt.h b/src/sqliteInt.h index 6e6ec72ac2..d4f8d23aa9 100644 --- a/src/sqliteInt.h +++ b/src/sqliteInt.h @@ -925,7 +925,8 @@ struct sqlite3 { #define SQLITE_IndexSort 0x04 /* Disable indexes for sorting */ #define SQLITE_IndexSearch 0x08 /* Disable indexes for searching */ #define SQLITE_IndexCover 0x10 /* Disable index covering table */ -#define SQLITE_OptMask 0x1f /* Mask of all disablable opts */ +#define SQLITE_GroupByOrder 0x20 /* Disable GROUPBY cover of ORDERBY */ +#define SQLITE_OptMask 0xff /* Mask of all disablable opts */ /* ** Possible values for the sqlite.magic field. @@ -2689,6 +2690,7 @@ void sqlite3Vacuum(Parse*); int sqlite3RunVacuum(char**, sqlite3*); char *sqlite3NameFromToken(sqlite3*, Token*); int sqlite3ExprCompare(Expr*, Expr*); +int sqlite3ExprListCompare(ExprList*, ExprList*); void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*); void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*); Vdbe *sqlite3GetVdbe(Parse*);