Change the LEFT JOIN strength reduction optimization so that assumes that

virtual table constraints can be true even if terms within the constraint
are NULL.  This works around dodgy virtual table implementations.

FossilOrigin-Name: cbb977fe1908431f3aad8e67668588b119e7d491724f2042af436f509a4f6623

diff --git a/manifest b/manifest
index 2802bd747a13101a331fcae67a05f3961d902b25..ebec2f1e00b9371b8c519811a63a311264449d6d 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Version\s3.23.0
-D 2018-04-02T11:04:16.044
+C Change\sthe\sLEFT\sJOIN\sstrength\sreduction\soptimization\sso\sthat\sassumes\sthat\nvirtual\stable\sconstraints\scan\sbe\strue\seven\sif\sterms\swithin\sthe\sconstraint\nare\sNULL.\s\sThis\sworks\saround\sdodgy\svirtual\stable\simplementations.
+D 2018-04-03T14:04:48.605
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 7016fc56c6b9bfe5daac4f34be8be38d8c0b5fab79ccbfb764d3b23bf1c6fff3
@@ -443,7 +443,7 @@ F src/date.c ebe1dc7c8a347117bb02570f1a931c62dd78f4a2b1b516f4837d45b7d6426957
 F src/dbpage.c 8db4c97f630e7d83f884ea75caf1ffd0988c160e9d530194d93721c80821e0f6
 F src/dbstat.c edabb82611143727511a45ca0859b8cd037851ebe756ae3db289859dd18b6f91
 F src/delete.c 20c8788451dc737a967c87ea53ad43544d617f5b57d32ccce8bd52a0daf9e89b
-F src/expr.c 51500461dcd4d0873a938bf188d03076d6712d70ff00a0f0d65621edf4e521c6
+F src/expr.c 0d4345e0e153cd6082ece69b4a0fdd0934d15bcd3925c74063cb8f65219a6f3c
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c d617daf66b5515e2b42c1405b2b4984c30ca50fb705ab164271a9bf66c69e331
 F src/func.c 94f42cba2cc1c34aeaa441022ba0170ec3fec4bba54db4e0ded085c6dc0fdc51
@@ -1717,10 +1717,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P b850dd159918af568c55c00ff146ba9c9c04d33ff384fe1eb0ad74164bc401bb
-R 7b7a30931830e96714db59b77704b857
-T +bgcolor * #d0c0ff
-T +sym-release *
-T +sym-version-3.23.0 *
+P 736b53f57f70b23172c30880186dce7ad9baa3b74e3838cae5847cffb98f5cd2
+R a6d2722715be08607b96fd599acd9dc9
 U drh
-Z 386b4344740e610e0c3078bd00d99ed8
+Z 96e5d106455d94d4a1b52de8a15d2af8

diff --git a/manifest.uuid b/manifest.uuid
index 8710d6d235ca97d6a305120c997d6120cbe76704..6f3888b7ab0119cdfebee9c1b40db7c5318aa7f2 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-736b53f57f70b23172c30880186dce7ad9baa3b74e3838cae5847cffb98f5cd2
\ No newline at end of file
+cbb977fe1908431f3aad8e67668588b119e7d491724f2042af436f509a4f6623
\ No newline at end of file

diff --git a/src/expr.c b/src/expr.c
index 14bd06a860e0cf1201dda29572e6cf6a3287f03e..5180044a5dad84fe1e49c7a969c09114f67c2eed 100644 (file)
--- a/src/expr.c
+++ b/src/expr.c
@@ -5037,6 +5037,27 @@ static int impliesNotNullRow(Walker *pWalker, Expr *pExpr){
         return WRC_Abort;
       }
       return WRC_Prune;
+
+    /* Virtual tables are allowed to use constraints like x=NULL.  So
+    ** a term of the form x=y does not prove that y is not null if x
+    ** is the column of a virtual table */
+    case TK_EQ:
+    case TK_NE:
+    case TK_LT:
+    case TK_LE:
+    case TK_GT:
+    case TK_GE:
+      testcase( pExpr->op==TK_EQ );
+      testcase( pExpr->op==TK_NE );
+      testcase( pExpr->op==TK_LT );
+      testcase( pExpr->op==TK_LE );
+      testcase( pExpr->op==TK_GT );
+      testcase( pExpr->op==TK_GE );
+      if( (pExpr->pLeft->op==TK_COLUMN && IsVirtual(pExpr->pLeft->pTab))
+       || (pExpr->pRight->op==TK_COLUMN && IsVirtual(pExpr->pRight->pTab))
+      ){
+       return WRC_Prune;
+      }
     default:
       return WRC_Continue;
   }