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

diff --git a/manifest b/manifest
index 438c37caf502be92a2841b2890af3d4c77b22560..f2bb25a6d4bb12b081b60442194855c880381903 100644 (file)
--- 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=
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diff --git a/manifest.uuid b/manifest.uuid
index 736cbd93889506933fb6c73b06de576cf6e3c776..8feb63902d7cf2993ec3866d4283006c287e3275 100644 (file)
--- 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 034088fafcefb70be2b0f4040b0d9c261c372200..70526aea612a2f68e73acd959bbbc17a378f8362 100644 (file)
--- 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; i<pA->x.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; i<pA->nExpr; 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 47e409ffc8a6750cab0c8190adf73031a0352493..9a016039a8e89bf21e4f3f7fa2a5016b0b20c007 100644 (file)
--- 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 6e6ec72ac2aaf876ac810d78821f11290726f77d..d4f8d23aa9481c64304821d2a024d372a8653000 100644 (file)
--- 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*);