Candidate fix for ticket #3082. Test cases needed. (CVS 5047)

FossilOrigin-Name: f6313311ddfb1ee2d6660b9be99afe721a8a9aff

manifest

@@ -1,5 +1,5 @@
-C Remove\stwo\smore\sunused\sfiles.\s(CVS\s5046)
-D 2008-04-24T22:57:29
+C Candidate\sfix\sfor\sticket\s#3082.\sTest\scases\sneeded.\s(CVS\s5047)
+D 2008-04-25T00:08:38
 F Makefile.arm-wince-mingw32ce-gcc ac5f7b2cef0cd850d6f755ba6ee4ab961b1fadf7
 F Makefile.in 25b3282a4ac39388632c2fb0e044ff494d490952
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -94,7 +94,7 @@ F src/callback.c 77b302b0d41468dcda78c70e706e5b84577f0fa0
 F src/complete.c 4cf68fd75d60257524cbe74f87351b9848399131
 F src/date.c e41ce4513fb0e359dc678d6bddb4ace135fe365d
 F src/delete.c e4bd53c46969c9fb05cfbba4abc0c93a923f8072
-F src/expr.c d5733edd985926fd94e7d51b3763084f7915e2c3
+F src/expr.c 6a6f37005921314b1ae7c3ed4fab03c58fd5e647
 F src/fault.c 83057e86815d473e526f7df0b0108dfdd022ff23
 F src/func.c c9e8c7ff4c45027edee89bde7adbf86a3a3b2afe
 F src/hash.c 522a8f5a23cf18fe5845afee7263c5be76c25ca2
@@ -630,7 +630,7 @@ F www/tclsqlite.tcl 8be95ee6dba05eabcd27a9d91331c803f2ce2130
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl fc46eae081251c3c181bd79c5faef8195d7991a5
-P 0d04ccd97841bbbda564cc6ae5da057ee3888fa3
-R d5c9fc7dffd786a749d8abc27197263d
+P a400faf51970b312e9d8c8b4fa099558cc620b69
+R 38bfb0a4f4b6d7e46cc483b5953eff78
 U drh
-Z 7362658de5fb5aa041e57c1c0e6c3d9d
+Z b2d1f6c45fdfbcc2b1867a8bfdc2ffb0

manifest.uuid

@@ -1 +1 @@
-a400faf51970b312e9d8c8b4fa099558cc620b69
+f6313311ddfb1ee2d6660b9be99afe721a8a9aff

src/expr.c

@@ -12,7 +12,7 @@
 ** This file contains routines used for analyzing expressions and
 ** for generating VDBE code that evaluates expressions in SQLite.
 **
-** $Id: expr.c,v 1.368 2008/04/24 12:36:35 danielk1977 Exp $
+** $Id: expr.c,v 1.369 2008/04/25 00:08:38 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -1576,6 +1576,45 @@ struct QueryCoder {
   #define sqlite3_enable_in_opt 1
 #endif
 
+/*
+** Return true if the IN operator optimization is enabled and
+** the SELECT statement p exists and is of the
+** simple form:
+**
+**     SELECT <column> FROM <table>
+**
+** If this is the case, it may be possible to use an existing table
+** or index instead of generating an epheremal table.
+*/
+#ifndef SQLITE_OMIT_SUBQUERY
+static int isCandidateForInOpt(Select *p){
+  SrcList *pSrc;
+  ExprList *pEList;
+  Table *pTab;
+  if( !sqlite3_enable_in_opt ) return 0; /* IN optimization must be enabled */
+  if( p==0 ) return 0;                   /* right-hand side of IN is SELECT */
+  if( p->pPrior ) return 0;              /* Not a compound SELECT */
+  if( p->isDistinct ) return 0;          /* No DISTINCT keyword */
+  if( p->isAgg ) return 0;               /* Contains no aggregate functions */
+  if( p->pGroupBy ) return 0;            /* Has no GROUP BY clause */
+  if( p->pLimit ) return 0;              /* Has no LIMIT clause */
+  if( p->pOffset ) return 0;
+  if( p->pWhere ) return 0;              /* Has no WHERE clause */
+  pSrc = p->pSrc;
+  if( pSrc==0 ) return 0;                /* A single table in the FROM clause */
+  if( pSrc->nSrc!=1 ) return 0;
+  if( pSrc->a[0].pSelect ) return 0;     /* FROM clause is not a subquery */
+  pTab = pSrc->a[0].pTab;
+  if( pTab==0 ) return 0;
+  if( pTab->pSelect ) return 0;          /* FROM clause is not a view */
+  if( IsVirtual(pTab) ) return 0;        /* FROM clause not a virtual table */
+  pEList = p->pEList;
+  if( pEList->nExpr!=1 ) return 0;       /* One column in the result set */
+  if( pEList->a[0].pExpr->op!=TK_COLUMN ) return 0; /* Result is a column */
+  return 1;
+}
+#endif /* SQLITE_OMIT_SUBQUERY */
+
 /*
 ** This function is used by the implementation of the IN (...) operator.
 ** It's job is to find or create a b-tree structure that may be used
@@ -1621,14 +1660,8 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int mustBeUnique){
   ** If this is the case, it may be possible to use an existing table
   ** or index instead of generating an epheremal table.
   */
-  if( sqlite3_enable_in_opt
-   && (p=pX->pSelect)!=0 && !p->pPrior
-   && !p->isDistinct && !p->isAgg && !p->pGroupBy
-   && p->pSrc && p->pSrc->nSrc==1 && !p->pSrc->a[0].pSelect
-   && p->pSrc->a[0].pTab && !p->pSrc->a[0].pTab->pSelect
-   && p->pEList->nExpr==1 && p->pEList->a[0].pExpr->op==TK_COLUMN
-   && !p->pLimit && !p->pOffset && !p->pWhere
-  ){
+  p = pX->pSelect;
+  if( isCandidateForInOpt(p) ){
     sqlite3 *db = pParse->db;
     Index *pIdx;
     Expr *pExpr = p->pEList->a[0].pExpr;