Also make sure an index that is a proper subset of some other index has a

higher cost than that other index. Add test cases. FossilOrigin-Name: b7830d232b073a197aa1092e78cb24e88cb10fd3
2014-03-31 19:49:00 +00:00 · 2014-03-31 19:49:00 +00:00 · 3fb183d2f7
commit 3fb183d2f7
parent 53cd10afcd
4 changed files with 185 additions and 37 deletions
--- a/13
+++ b/13
@ -1,5 +1,5 @@
-C Make\ssure\sthat\san\sindex\sthat\scovers\sa\sproper\ssuperset\sof\sthe\sWHERE\sclause\nterms\sof\ssome\sother\sindex\shas\sa\slower\scost\sthan\sthe\sother\sindex.
-D 2014-03-31T18:24:18.867
+C Also\smake\ssure\san\sindex\sthat\sis\sa\sproper\ssubset\sof\ssome\sother\sindex\shas\sa\nhigher\scost\sthan\sthat\sother\sindex.\s\sAdd\stest\scases.
+D 2014-03-31T19:49:00.374
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@ -291,7 +291,7 @@ F src/vtab.c 21b932841e51ebd7d075e2d0ad1415dce8d2d5fd
 F src/wal.c 76e7fc6de229bea8b30bb2539110f03a494dc3a8
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
 F src/walker.c 11edb74d587bc87b33ca96a5173e3ec1b8389e45
-F src/where.c 50ac3154473b5c8df15c7b8dbd19da385fa859e1
+F src/where.c 182f16d91060418dfcc7401d24e43d8ec24e026c
 F src/whereInt.h 2564055b440e44ebec8b47f237bbccae6719b7af
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@ -1093,6 +1093,7 @@ F test/whereD.test 6c2feb79ef1f68381b07f39017fe5f9b96da8d62
 F test/whereE.test b3a055eef928c992b0a33198a7b8dc10eea5ad2f
 F test/whereF.test 5b2ba0dbe8074aa13e416b37c753991f0a2492d7
 F test/whereG.test eb3a46b3eaf38e25e3013433b2db8a25a866c215
+F test/whereH.test e4b07f7a3c2f5d31195cd33710054c78667573b2
 F test/wherelimit.test 5e9fd41e79bb2b2d588ed999d641d9c965619b31
 F test/wild001.test bca33f499866f04c24510d74baf1e578d4e44b1c
 F test/win32heap.test ea19770974795cff26e11575e12d422dbd16893c
@ -1159,7 +1160,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
-P 8f869ca7a6eaa9ca7a08102290e6c606735f9090
-R 76b8d8088ba83ec014dc8bf476fa6749
+P ea8b0910040198751551b0b960e6b783913607df
+R 176e1ff66c14893be5de17b3890f1972
 U drh
-Z ecebe13d1c9f7ea1da970c5f6118dc52
+Z 3bf4657410567331f2f5534ba4eae60e
--- a/manifest.uuid
+++ b/manifest.uuid
@ -1 +1 @@
-ea8b0910040198751551b0b960e6b783913607df
+b7830d232b073a197aa1092e78cb24e88cb10fd3
--- a/src/where.c
+++ b/src/where.c
@ -3712,46 +3712,54 @@ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
 }

 /*
-** Compare every WhereLoop X on the list p against pTemplate.  If:
+** Return TRUE if the set of WHERE clause terms used by pA is a proper
+** subset of the WHERE clause terms used by pB.
+*/
+static int whereLoopProperSubset(const WhereLoop *pA, const WhereLoop *pB){
+  int i, j;
+  if( pA->nLTerm>=pB->nLTerm ) return 0;
+  for(j=0, i=pA->nLTerm-1; i>=0 && j>=0; i--){
+    for(j=pB->nLTerm-1; j>=0; j--){
+      if( pB->aLTerm[j]==pA->aLTerm[i] ) break;
+    }
+  }
+  return j>=0;
+}
+
+/*
+** Try to adjust the cost of WhereLoop pTemplate upwards or downwards so
+** that:
 **
-**    (1) both X and pTemplate refer to the same table, and
-**    (2) both X and pTemplate use a single index, and
-**    (3) pTemplate uses all the same WHERE clause terms as X plus
-**        at least one more term,
+**   (1) pTemplate costs less than any other WhereLoops that are a proper
+**       subset of pTemplate
 **
-** then make sure the cost pTemplate is less than the cost of X, adjusting
-** the cost of pTemplate downward if necessary.
+**   (2) pTemplate costs more than any other WhereLoops for which pTemplate
+**       is a proper subset.
 **
-** Example: When computing the query plan for the SELECT below:
-**
-**     CREATE TABLE t1(a,b,c,d);
-**     CREATE INDEX t1abc ON t1(a,b,c);
-**     CREATE INDEX t1bc ON t1(b,c);
-**     SELECT d FROM t1 WHERE a=? AND b=? AND c>=? ORDER BY c;
-** 
-** Make sure the cost of using three three columns of index t1abc is less
-** than the cost of using both columns of t1bc.
+** To say "WhereLoop X is a proper subset of Y" means that X uses fewer
+** WHERE clause terms than Y and that every WHERE clause term used by X is
+** also used by Y.
 */
 static void whereLoopAdjustCost(const WhereLoop *p, WhereLoop *pTemplate){
  if( (pTemplate->wsFlags & WHERE_INDEXED)==0 ) return;
-  if( pTemplate->nLTerm==0 ) return;
  for(; p; p=p->pNextLoop){
-    if( p->iTab==pTemplate->iTab
-     && (p->wsFlags & WHERE_INDEXED)!=0
-     && p->nLTerm<pTemplate->nLTerm
+    if( p->iTab!=pTemplate->iTab ) continue;
+    if( (p->wsFlags & WHERE_INDEXED)==0 ) continue;
+    if( p->nLTerm<pTemplate->nLTerm
     && (p->rRun<pTemplate->rRun || (p->rRun==pTemplate->rRun &&
                                     p->nOut<=pTemplate->nOut))
+     && whereLoopProperSubset(p, pTemplate)
    ){
-      int i, j;
-      for(j=0, i=p->nLTerm-1; i>=0 && j>=0; i--){
-        for(j=pTemplate->nLTerm-1; j>=0; j--){
-          if( pTemplate->aLTerm[j]==p->aLTerm[i] ) break;
-        }
-      }
-      if( j>=0 ){
-        pTemplate->rRun = p->rRun;
-        pTemplate->nOut = p->nOut - 1;
-      }
+      pTemplate->rRun = p->rRun;
+      pTemplate->nOut = p->nOut - 1;
+    }else
+    if( p->nLTerm>pTemplate->nLTerm
+     && (p->rRun>pTemplate->rRun || (p->rRun==pTemplate->rRun &&
+                                     p->nOut>=pTemplate->nOut))
+     && whereLoopProperSubset(pTemplate, p)
+    ){
+      pTemplate->rRun = p->rRun;
+      pTemplate->nOut = p->nOut + 1;
    }
  }
 }
--- a/test/whereH.test
+++ b/test/whereH.test
@ -0,0 +1,139 @@
+# 2014-03-31
+#
+# 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.
+#
+#***********************************************************************
+# 
+# Test cases for query planning decisions where one candidate index
+# covers a proper superset of the WHERE clause terms of another
+# candidate index.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+do_execsql_test whereH-1.1 {
+  CREATE TABLE t1(a,b,c,d);
+  CREATE INDEX t1abc ON t1(a,b,c);
+  CREATE INDEX t1bc ON t1(b,c);
+
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c>=? ORDER BY c;
+} {/INDEX t1abc /}
+do_execsql_test whereH-1.2 {
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c>=? ORDER BY c;
+} {~/TEMP B-TREE FOR ORDER BY/}
+
+do_execsql_test whereH-2.1 {
+  DROP TABLE t1;
+  CREATE TABLE t1(a,b,c,d);
+  CREATE INDEX t1bc ON t1(b,c);
+  CREATE INDEX t1abc ON t1(a,b,c);
+
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c>=? ORDER BY c;
+} {/INDEX t1abc /}
+do_execsql_test whereH-2.2 {
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c>=? ORDER BY c;
+} {~/TEMP B-TREE FOR ORDER BY/}
+
+do_execsql_test whereH-3.1 {
+  DROP TABLE t1;
+  CREATE TABLE t1(a,b,c,d,e);
+  CREATE INDEX t1cd ON t1(c,d);
+  CREATE INDEX t1bcd ON t1(b,c,d);
+  CREATE INDEX t1abcd ON t1(a,b,c,d);
+
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {/INDEX t1abcd /}
+do_execsql_test whereH-3.2 {
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {~/TEMP B-TREE FOR ORDER BY/}
+
+do_execsql_test whereH-4.1 {
+  DROP TABLE t1;
+  CREATE TABLE t1(a,b,c,d,e);
+  CREATE INDEX t1cd ON t1(c,d);
+  CREATE INDEX t1abcd ON t1(a,b,c,d);
+  CREATE INDEX t1bcd ON t1(b,c,d);
+
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {/INDEX t1abcd /}
+do_execsql_test whereH-4.2 {
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {~/TEMP B-TREE FOR ORDER BY/}
+
+do_execsql_test whereH-5.1 {
+  DROP TABLE t1;
+  CREATE TABLE t1(a,b,c,d,e);
+  CREATE INDEX t1bcd ON t1(b,c,d);
+  CREATE INDEX t1cd ON t1(c,d);
+  CREATE INDEX t1abcd ON t1(a,b,c,d);
+
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {/INDEX t1abcd /}
+do_execsql_test whereH-5.2 {
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {~/TEMP B-TREE FOR ORDER BY/}
+
+do_execsql_test whereH-6.1 {
+  DROP TABLE t1;
+  CREATE TABLE t1(a,b,c,d,e);
+  CREATE INDEX t1bcd ON t1(b,c,d);
+  CREATE INDEX t1abcd ON t1(a,b,c,d);
+  CREATE INDEX t1cd ON t1(c,d);
+
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {/INDEX t1abcd /}
+do_execsql_test whereH-6.2 {
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {~/TEMP B-TREE FOR ORDER BY/}
+
+do_execsql_test whereH-7.1 {
+  DROP TABLE t1;
+  CREATE TABLE t1(a,b,c,d,e);
+  CREATE INDEX t1abcd ON t1(a,b,c,d);
+  CREATE INDEX t1bcd ON t1(b,c,d);
+  CREATE INDEX t1cd ON t1(c,d);
+
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {/INDEX t1abcd /}
+do_execsql_test whereH-7.2 {
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {~/TEMP B-TREE FOR ORDER BY/}
+
+do_execsql_test whereH-8.1 {
+  DROP TABLE t1;
+  CREATE TABLE t1(a,b,c,d,e);
+  CREATE INDEX t1abcd ON t1(a,b,c,d);
+  CREATE INDEX t1cd ON t1(c,d);
+  CREATE INDEX t1bcd ON t1(b,c,d);
+
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {/INDEX t1abcd /}
+do_execsql_test whereH-8.2 {
+  EXPLAIN QUERY PLAN
+  SELECT d FROM t1 WHERE a=? AND b=? AND c=? AND d>=? ORDER BY d;
+} {~/TEMP B-TREE FOR ORDER BY/}
+
+
+
+finish_test