Minor optimizations for sub-selects in EXISTS(...) expressions: Discard any DISTINCT or ORDER BY clauses and do not calculate any column values. (CVS 4658)
FossilOrigin-Name: fbd17a8976cc9b4dd7c7c903d8beade9a7ef095f
diff --git a/manifest b/manifest
index 2ddab03..e4108d9 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Combine\sthe\seDest\sand\siParm\sarguments\sto\ssqlite3Select()\sinto\sa\ssingle\stype\s-\s"SelectDest".\s(CVS\s4657)
-D 2008-01-02T16:27:10
+C Minor\soptimizations\sfor\ssub-selects\sin\sEXISTS(...)\sexpressions:\sDiscard\sany\sDISTINCT\sor\sORDER\sBY\sclauses\sand\sdo\snot\scalculate\sany\scolumn\svalues.\s(CVS\s4658)
+D 2008-01-02T17:11:14
F Makefile.arm-wince-mingw32ce-gcc ac5f7b2cef0cd850d6f755ba6ee4ab961b1fadf7
F Makefile.in 30789bf70614bad659351660d76b8e533f3340e9
F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -131,12 +131,12 @@
F src/prepare.c 7aeba7851773fbe3950a26b35d3389bef0eb1c62
F src/printf.c eb27822ba2eec669161409ca31279a24c26ac910
F src/random.c 4a22746501bf36b0a088c66e38dde5daba6a35da
-F src/select.c 6a3790a03f10b2dfce9011d93e817b2cff7746d4
+F src/select.c cc4064f931c32139f97b43572180a99eff08e759
F src/server.c 087b92a39d883e3fa113cae259d64e4c7438bc96
F src/shell.c 77895a54c2082157e169c857a2e244525ec25af7
F src/sqlite.h.in 2a7e3776534bbe6ff2cdc058f3abebe91e7e429f
F src/sqlite3ext.h a93f59cdee3638dc0c9c086f80df743a4e68c3cb
-F src/sqliteInt.h ff7a5de4ac31a974eab8cc5286fef01d4ed2e148
+F src/sqliteInt.h dc0f9180d4aa50fce261d7ae7387952e02752165
F src/sqliteLimit.h ee4430f88f69bf63527967bb35ca52af7b0ccb1e
F src/table.c 1aeb9eab57b4235db86fe15a35dec76fb445a9c4
F src/tclsqlite.c 9923abeffc9b3d7dad58e92b319661521f60debf
@@ -603,7 +603,7 @@
F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
F www/whentouse.tcl fc46eae081251c3c181bd79c5faef8195d7991a5
-P 4c7f35da7751c61a9b61b1d95adddcc37fff3266
-R cf4761a43ed1fe7db5bce1f482fb074b
+P 86dcdfe6d7d629618ccb3c3ff0ca09f2da2d06c7
+R 982c17244c2079cbd0e5e4196c9007ad
U danielk1977
-Z 493527b5521ff75db65bcee76afc559a
+Z 3000de620d66b1fa18c8d40dc95b7145
diff --git a/manifest.uuid b/manifest.uuid
index 28f9cf8..9a124b5 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-86dcdfe6d7d629618ccb3c3ff0ca09f2da2d06c7
\ No newline at end of file
+fbd17a8976cc9b4dd7c7c903d8beade9a7ef095f
\ No newline at end of file
diff --git a/src/select.c b/src/select.c
index 34b7d31..a854e3e 100644
--- a/src/select.c
+++ b/src/select.c
@@ -12,7 +12,7 @@
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
-** $Id: select.c,v 1.376 2008/01/02 16:27:10 danielk1977 Exp $
+** $Id: select.c,v 1.377 2008/01/02 17:11:14 danielk1977 Exp $
*/
#include "sqliteInt.h"
@@ -548,7 +548,10 @@
for(i=0; i<nColumn; i++){
sqlite3VdbeOp3Int(v, OP_Column, srcTab, i, iMem+i+1);
}
- }else{
+ }else if( eDest!=SRT_Exists ){
+ /* If the destination is an EXISTS(...) expression, the actual
+ ** values returned by the SELECT are not required.
+ */
for(i=0; i<n; i++){
sqlite3ExprIntoReg(pParse, pEList->a[i].pExpr, iMem+i+1);
}
@@ -3143,6 +3146,13 @@
pOrderBy = p->pOrderBy;
if( IgnorableOrderby(pDest) ){
p->pOrderBy = 0;
+
+ /* In these cases the DISTINCT operator makes no difference to the
+ ** results, so remove it if it were specified.
+ */
+ assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union ||
+ pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard);
+ p->isDistinct = 0;
}
if( sqlite3SelectResolve(pParse, p, 0) ){
goto select_end;
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 89b337b..c25f80e 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -11,7 +11,7 @@
*************************************************************************
** Internal interface definitions for SQLite.
**
-** @(#) $Id: sqliteInt.h,v 1.629 2008/01/02 16:27:10 danielk1977 Exp $
+** @(#) $Id: sqliteInt.h,v 1.630 2008/01/02 17:11:14 danielk1977 Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_
@@ -1330,18 +1330,18 @@
*/
#define SRT_Union 1 /* Store result as keys in an index */
#define SRT_Except 2 /* Remove result from a UNION index */
-#define SRT_Discard 3 /* Do not save the results anywhere */
+#define SRT_Exists 3 /* Store 1 if the result is not empty */
+#define SRT_Discard 4 /* Do not save the results anywhere */
/* The ORDER BY clause is ignored for all of the above */
#define IgnorableOrderby(X) ((X->eDest)<=SRT_Discard)
-#define SRT_Callback 4 /* Invoke a callback with each row of result */
-#define SRT_Mem 5 /* Store result in a memory cell */
-#define SRT_Set 6 /* Store non-null results as keys in an index */
-#define SRT_Table 7 /* Store result as data with an automatic rowid */
-#define SRT_EphemTab 8 /* Create transient tab and store like SRT_Table */
-#define SRT_Subroutine 9 /* Call a subroutine to handle results */
-#define SRT_Exists 10 /* Store 1 if the result is not empty */
+#define SRT_Callback 5 /* Invoke a callback with each row of result */
+#define SRT_Mem 6 /* Store result in a memory cell */
+#define SRT_Set 7 /* Store non-null results as keys in an index */
+#define SRT_Table 8 /* Store result as data with an automatic rowid */
+#define SRT_EphemTab 9 /* Create transient tab and store like SRT_Table */
+#define SRT_Subroutine 10 /* Call a subroutine to handle results */
/*
** A structure used to customize the behaviour of sqlite3Select(). See