From: drh <drh@noemail.net>
Date: Fri, 9 Nov 2012 18:22:26 +0000 (+0000)
Subject: Disable the table selection rule that tried to prevent full table scans from
X-Git-Tag: version-3.7.15~41^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fheads%2Finner-loop-cost;p=thirdparty%2Fsqlite.git

Disable the table selection rule that tried to prevent full table scans from
migrating to the outer loop unless they were optimal.  The new scaling of
outer-loop costs by cost of inner loops obviates the need for that step.  And,
in fact, that step causes problems with the new inner-loop cost accounting.

FossilOrigin-Name: 51bfd63b7f9fe53831570ad124c932cb3582b104
---

diff --git a/manifest b/manifest
index 65706de517..66c67bce3f 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Try\sto\stake\sinto\saccount\sthe\scost\sof\sinner\sloops\swhen\sselecting\swhich\stable\nof\sa\sjoin\sto\suse\sfor\sthe\souter\sloop.
-D 2012-11-09T17:59:26.161
+C Disable\sthe\stable\sselection\srule\sthat\stried\sto\sprevent\sfull\stable\sscans\sfrom\nmigrating\sto\sthe\souter\sloop\sunless\sthey\swere\soptimal.\s\sThe\snew\sscaling\sof\s\nouter-loop\scosts\sby\scost\sof\sinner\sloops\sobviates\sthe\sneed\sfor\sthat\sstep.\s\sAnd,\nin\sfact,\sthat\sstep\scauses\sproblems\swith\sthe\snew\sinner-loop\scost\saccounting.
+D 2012-11-09T18:22:26.026
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 82c41c0ed4cc94dd3cc7d498575b84c57c2c2384
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -249,7 +249,7 @@ F src/vtab.c b05e5f1f4902461ba9f5fc49bb7eb7c3a0741a83
 F src/wal.c f5c7b5027d0ed0e9bc9afeb4a3a8dfea762ec7d2
 F src/wal.h 29c197540b19044e6cd73487017e5e47a1d3dac6
 F src/walker.c 3d75ba73de15e0f8cd0737643badbeb0e002f07b
-F src/where.c b97f14d4ce618ceb18138238b1bd028cf02014b4
+F src/where.c 832e33fefbe5ba751c1f5a06e63de98be95e56f2
 F test/8_3_names.test 631ea964a3edb091cf73c3b540f6bcfdb36ce823
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
 F test/aggnested.test 45c0201e28045ad38a530b5a144b73cd4aa2cfd6
@@ -1024,10 +1024,7 @@ F tool/vdbe-compress.tcl f12c884766bd14277f4fcedcae07078011717381
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
 F tool/win/sqlite.vsix 97894c2790eda7b5bce3cc79cb2a8ec2fde9b3ac
-P 82eb7eadb8c76b3af8c811d791f87a634c35935f
-R 6e69028f10fbf48578845dd76c89b910
-T *branch * inner-loop-cost
-T *sym-inner-loop-cost *
-T -sym-trunk *
+P 942556342a332b04a11169bb04f387d741ef9488
+R 283b8e4433f3480f37a4748d3a98dd6b
 U drh
-Z 386f6fc4840a28b57311013bb9458533
+Z d761059332f6b35837425e120092c25f
diff --git a/manifest.uuid b/manifest.uuid
index 85eae6eacd..6f8dcc7f72 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-942556342a332b04a11169bb04f387d741ef9488
\ No newline at end of file
+51bfd63b7f9fe53831570ad124c932cb3582b104
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index 5fa40994fe..20bd90979e 100644
--- a/src/where.c
+++ b/src/where.c
@@ -4744,16 +4744,6 @@ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
   }
 }
 
-/*
-** Return TRUE if the wsFlags indicate that a full table scan (or a
-** full scan of a covering index) is indicated.
-*/
-static int isFullscan(unsigned wsFlags){
-  if( wsFlags & WHERE_COVER_SCAN ) return 1;
-  if( (wsFlags & WHERE_NOT_FULLSCAN)==0 ) return 1;
-  return 0;
-}
-
 
 /*
 ** Generate the beginning of the loop used for WHERE clause processing.
@@ -5132,8 +5122,8 @@ WhereInfo *sqlite3WhereBegin(
         **       yet run.  (In other words, it must not depend on tables
         **       in inner loops.)
         **
-        **   (2) A full-table-scan plan cannot supercede indexed plan unless
-        **       the full-table-scan is an "optimal" plan as defined above.
+        **   (2) (This rule was removed on 2012-11-09.  The scaling of the
+        **       cost using the optimal scan cost made this rule obsolete.)
         **
         **   (3) All tables have an INDEXED BY clause or this table lacks an
         **       INDEXED BY clause or this table uses the specific
@@ -5148,9 +5138,6 @@ WhereInfo *sqlite3WhereBegin(
         **       is defined by the compareCost() function above. 
         */
         if( (sWBI.cost.used&sWBI.notValid)==0                    /* (1) */
-            && (bestJ<0 || (notIndexed&m)!=0                     /* (2) */
-                || isFullscan(bestPlan.plan.wsFlags)
-                || !isFullscan(sWBI.cost.plan.wsFlags))
             && (nUnconstrained==0 || sWBI.pSrc->pIndex==0        /* (3) */
                 || NEVER((sWBI.cost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0))
             && (bestJ<0 || compareCost(&sWBI.cost, &bestPlan))   /* (4) */