Fix a problem in calculating the costs of "OR" scans.

FossilOrigin-Name: 9bbca48b42e4fe16f2188e18dc736da30a96435c

manifest

@@ -1,5 +1,5 @@
-C Modify\sthe\sway\sthe\scosts\sof\svarious\squery\splans\sare\sestimated.\sIf\sthe\suser\ssupplies\sa\slikelihood()\svalue\s(or\sequivalent)\son\san\sindexed\sWHERE\sconstraint,\suse\sit\sto\sestimate\sthe\snumber\sof\sindex\srows\svisited.
-D 2014-04-30T15:22:25.359
+C Fix\sa\sproblem\sin\scalculating\sthe\scosts\sof\s"OR"\sscans.
+D 2014-04-30T18:11:55.566
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -292,7 +292,7 @@ F src/vtab.c 21b932841e51ebd7d075e2d0ad1415dce8d2d5fd
 F src/wal.c 76e7fc6de229bea8b30bb2539110f03a494dc3a8
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
 F src/walker.c 11edb74d587bc87b33ca96a5173e3ec1b8389e45
-F src/where.c 4aeb1caa0a16c76e0c0566af4c64ba003836a0aa
+F src/where.c 3eaf3d241d86452c0f21aa3fe2b5df25d8c99a24
 F src/whereInt.h 6804c2e5010378568c2bb1350477537755296a46
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@@ -407,7 +407,7 @@ F test/corruptF.test be9fde98e4c93648f1ba52b74e5318edc8f59fe4
 F test/corruptG.test 1ab3bf97ee7bdba70e0ff3ba2320657df55d1804
 F test/corruptH.test 88ed71a086e13591c917aac6de32750e7c7281cb
 F test/corruptI.test b3e4203d420490fc3d3062711597bc1dea06a789
-F test/cost.test 3f7904d623ef8dc6e55f2206db5ce0549077b438
+F test/cost.test 04842adec34311d70c3f3c5fd698b22be54138fd
 F test/count.test 42a251178e32f617eda33f76236a7f79825a50b5
 F test/coveridxscan.test cdb47d01acc4a634a34fd25abe85189e0d0f1e62
 F test/crash.test fb9dc4a02dcba30d4aa5c2c226f98b220b2b959f
@@ -1166,7 +1166,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
-P af2cbe64adab5f9e3b0f3da00d06428088589d7f 05e6e16cb28c9ffb4596bd2ef81f687c5403ecbb
-R 20e49e26218874ddfe5fb9438df8f580
+P 90e36676476e8db00658772e6c938242f766d306
+R cf0f5a4a25fa17ee63b35d342904cb95
 U dan
-Z 75da520dd73c7e9f7e5ee96ec52c5c59
+Z 15897e765882c5d27e5f655ffd8d3c94

manifest.uuid

@@ -1 +1 @@
-90e36676476e8db00658772e6c938242f766d306
+9bbca48b42e4fe16f2188e18dc736da30a96435c

src/where.c

@@ -4738,7 +4738,7 @@ static int whereLoopAddOr(WhereLoopBuilder *pBuilder, Bitmask mExtra){
   int iCur;
   WhereClause tempWC;
   WhereLoopBuilder sSubBuild;
-  WhereOrSet sSum, sCur, sPrev;
+  WhereOrSet sSum, sCur;
   struct SrcList_item *pItem;
   
   pWC = pBuilder->pWC;
@@ -4794,6 +4794,7 @@ static int whereLoopAddOr(WhereLoopBuilder *pBuilder, Bitmask mExtra){
           whereOrMove(&sSum, &sCur);
           once = 0;
         }else{
+          WhereOrSet sPrev;
           whereOrMove(&sPrev, &sSum);
           sSum.n = 0;
           for(i=0; i<sPrev.n; i++){
@@ -4812,7 +4813,19 @@ static int whereLoopAddOr(WhereLoopBuilder *pBuilder, Bitmask mExtra){
       pNew->iSortIdx = 0;
       memset(&pNew->u, 0, sizeof(pNew->u));
       for(i=0; rc==SQLITE_OK && i<sSum.n; i++){
-        pNew->rRun = sSum.a[i].rRun;
+        /* TUNING: Currently sSum.a[i].rRun is set to the sum of the costs
+        ** of all sub-scans required by the OR-scan. However, due to rounding
+        ** errors, it may be that the cost of the OR-scan is equal to its
+        ** most expensive sub-scan. Add the smallest possible penalty 
+        ** (equivalent to multiplying the cost by 1.07) to ensure that 
+        ** this does not happen. Otherwise, for WHERE clauses such as the
+        ** following where there is an index on "y":
+        **
+        **     WHERE likelihood(x=?, 0.99) OR y=?
+        **
+        ** the planner may elect to "OR" together a full-table scan and an
+        ** index lookup. And other similarly odd results.  */
+        pNew->rRun = sSum.a[i].rRun + 1;
         pNew->nOut = sSum.a[i].nOut;
         pNew->prereq = sSum.a[i].prereq;
         rc = whereLoopInsert(pBuilder, pNew);

test/cost.test

@@ -150,7 +150,6 @@ do_eqp_test 7.2 {
   0 0 0 {USE TEMP B-TREE FOR ORDER BY}
 }
 
-#set sqlite_where_trace 0xfff
 do_eqp_test 7.3 {
   SELECT rowid FROM t1
   WHERE (+b IS NULL AND c NOT NULL AND d NOT NULL)
@@ -160,6 +159,12 @@ do_eqp_test 7.3 {
   0 0 0 {SCAN TABLE t1}
 }
 
+do_eqp_test 7.4 {
+  SELECT rowid FROM t1 WHERE (+b IS NULL AND c NOT NULL) OR c IS NULL
+} {
+  0 0 0 {SCAN TABLE t1}
+}
+
 #-------------------------------------------------------------------------
 #
 reset_db