Prevent an automatic index from taking the place of a declared index.

FossilOrigin-Name: 4ece839d445ff578a449a339ab579a32e64c9d28

manifest

@@ -1,5 +1,5 @@
-C Add\sthe\sautoindex2.test\stesting\smodule.
-D 2014-06-17T13:23:36.416
+C Prevent\san\sautomatic\sindex\sfrom\staking\sthe\splace\sof\sa\sdeclared\sindex.
+D 2014-06-17T20:16:43.699
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in ed5e4aae4799f724699d5509fac2977786414dbb
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -296,7 +296,7 @@ F src/vtab.c 21b932841e51ebd7d075e2d0ad1415dce8d2d5fd
 F src/wal.c 264df50a1b33124130b23180ded2e2c5663c652a
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
 F src/walker.c 11edb74d587bc87b33ca96a5173e3ec1b8389e45
-F src/where.c cd3110c7dca304ecbdf2ed07b23205e90b10475b
+F src/where.c 0035f45de6a2f248e2ac57da16460858b2166089
 F src/whereInt.h 929c1349b5355fd44f22cee5c14d72b3329c58a6
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@@ -336,6 +336,7 @@ F test/auth3.test a4755e6a2a2fea547ffe63c874eb569e60a28eb5
 F test/autoinc.test c58912526998a39e11f66b533e23cfabea7f25b7
 F test/autoindex1.test 762ff3f8e25d852aae55c6462ca166a80c0cde61
 F test/autoindex2.test 60d2fc6f38364308ce73a9beb01b47ded38697de
+F test/autoindex3.test 8254f689c3241081fad52b7bea18ba53e07e14a2
 F test/autovacuum.test 941892505d2c0f410a0cb5970dfa1c7c4e5f6e74
 F test/autovacuum_ioerr2.test 8a367b224183ad801e0e24dcb7d1501f45f244b4
 F test/avtrans.test 0252654f4295ddda3b2cce0e894812259e655a85
@@ -1178,7 +1179,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P f270fb6e9e0b5e77f918081962008c6195ab1e36
-R 4590197fe44138640af30c15c42aaab1
+P ffe3fea47b8ba8ec4557f68243ef3ef5aac00dfd
+R b60de90301b6f096aa7fa9280f014db5
 U drh
-Z c2b8b2abeb08d5199560396ab0f820e5
+Z 58155d377c73e3b2e02e7af08e490e72

manifest.uuid

@@ -1 +1 @@
-ffe3fea47b8ba8ec4557f68243ef3ef5aac00dfd
+4ece839d445ff578a449a339ab579a32e64c9d28

src/where.c

@@ -3923,6 +3923,17 @@ static WhereLoop **whereLoopFindLesser(
     ** rSetup. Call this SETUP-INVARIANT */
     assert( p->rSetup>=pTemplate->rSetup );
 
+    /* Any loop using an appliation-defined index (or PRIMARY KEY or
+    ** UNIQUE constraint) with one or more == constraints is better
+    ** than an automatic index. */
+    if( (p->wsFlags & WHERE_AUTO_INDEX)!=0
+     && (pTemplate->wsFlags & WHERE_INDEXED)!=0
+     && (pTemplate->wsFlags & WHERE_COLUMN_EQ)!=0
+     && (p->prereq & pTemplate->prereq)==pTemplate->prereq
+    ){
+      break;
+    }
+
     /* If existing WhereLoop p is better than pTemplate, pTemplate can be
     ** discarded.  WhereLoop p is better if:
     **   (1)  p has no more dependencies than pTemplate, and
@@ -4047,7 +4058,7 @@ static int whereLoopInsert(WhereLoopBuilder *pBuilder, WhereLoop *pTemplate){
     WhereLoop *pToDel;
     while( *ppTail ){
       ppTail = whereLoopFindLesser(ppTail, pTemplate);
-      if( NEVER(ppTail==0) ) break;
+      if( ppTail==0 ) break;
       pToDel = *ppTail;
       if( pToDel==0 ) break;
       *ppTail = pToDel->pNextLoop;

test/autoindex3.test

@@ -0,0 +1,58 @@
+# 2014-06-17
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#*************************************************************************
+#
+# This file implements regression tests for SQLite library.  The
+# focus of this script is testing automatic index creation logic,
+# and specifically that an automatic index will not be created that
+# shadows a declared index.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+# The t1b and t2d indexes are not very selective.  It used to be that
+# the autoindex mechanism would create automatic indexes on t1(b) or
+# t2(d), make assumptions that they were reasonably selective, and use
+# them instead of t1b or t2d.  But that would be cheating, because the
+# automatic index cannot be any more selective than the real index.
+#
+# This test verifies that the cheat is no longer allowed.
+#
+do_execsql_test autoindex3-100 {
+  CREATE TABLE t1(a,b,x);
+  CREATE TABLE t2(c,d,y);
+  CREATE INDEX t1b ON t1(b);
+  CREATE INDEX t2d ON t2(d);
+  ANALYZE sqlite_master;
+  INSERT INTO sqlite_stat1 VALUES('t1','t1b','10000 500');
+  INSERT INTO sqlite_stat1 VALUES('t2','t2d','10000 500');
+  ANALYZE sqlite_master;
+  EXPLAIN QUERY PLAN SELECT * FROM t1, t2 WHERE d=b;
+} {~/AUTO/}
+
+# Automatic indexes can still be used if existing indexes do not
+# participate in == constraints.
+#
+do_execsql_test autoindex3-110 {
+  EXPLAIN QUERY PLAN SELECT * FROM t1, t2 WHERE d>b AND x=y;
+} {/AUTO/}
+do_execsql_test autoindex3-120 {
+  EXPLAIN QUERY PLAN SELECT * FROM t1, t2 WHERE d<b AND x=y;
+} {/AUTO/}
+do_execsql_test autoindex3-130 {
+  EXPLAIN QUERY PLAN SELECT * FROM t1, t2 WHERE d IS NULL AND x=y;
+} {/AUTO/}
+do_execsql_test autoindex3-140 {
+  EXPLAIN QUERY PLAN SELECT * FROM t1, t2 WHERE d IN (5,b) AND x=y;
+} {/AUTO/}
+
+
+finish_test