Index: src/where.c ================================================================== --- src/where.c +++ src/where.c @@ -3920,10 +3920,21 @@ /* whereLoopAddBtree() always generates and inserts the automatic index ** case first. Hence compatible candidate WhereLoops never have a larger ** 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 ** (2) p has an equal or lower cost than pTemplate @@ -4045,11 +4056,11 @@ ** p[] that are also supplated by pTemplate */ WhereLoop **ppTail = &p->pNextLoop; 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; #if WHERETRACE_ENABLED /* 0x8 */ if( sqlite3WhereTrace & 0x8 ){ ADDED test/autoindex3.test Index: test/autoindex3.test ================================================================== --- /dev/null +++ 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