From d4dae75f79580285a4c122a71404e68bab1ac895 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Wed, 11 Dec 2019 16:22:53 +0000
Subject: [PATCH] Strengthen check-in [83da4d4104ee1870] by ignoring *all*
 WHERE-clause constraints for a virtual table that is the right table of a
 LEFT JOIN, as such constraints are never useful. This fixes an issue
 discovered by Manuel Rigger.

FossilOrigin-Name: 840de36df1aaeb4bad9a7c18e97cc560ba3b8c629c4520a05bc456d67b3347b9
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 src/where.c   | 19 +++++++------------
 3 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/manifest b/manifest
index 8de7ccc479..11d39620c8 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C When\strying\sto\sdrop\sa\svirtual\stable\sthat\shas\sno\sxDestroy\smethod,\sinvoke\nthe\sxDisconnect\smethod\srather\sthan\sdoing\snothing,\sto\savoid\sa\smemory\sleak.
-D 2019-12-11T15:07:09.012
+C Strengthen\scheck-in\s[83da4d4104ee1870]\sby\signoring\s*all*\sWHERE-clause\nconstraints\sfor\sa\svirtual\stable\sthat\sis\sthe\sright\stable\sof\sa\sLEFT\sJOIN,\s\nas\ssuch\sconstraints\sare\snever\suseful.\nThis\sfixes\san\sissue\sdiscovered\sby\sManuel\sRigger.
+D 2019-12-11T16:22:53.344
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -613,7 +613,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 15a2845769f51ba132f9cf0b2c7a6887a91fc8437892dbcce9fcdc68b66d60a1
 F src/wal.h 606292549f5a7be50b6227bd685fa76e3a4affad71bb8ac5ce4cb5c79f6a176a
 F src/walker.c a137468bf36c92e64d2275caa80c83902e3a0fc59273591b96c6416d3253d05d
-F src/where.c bb2d3c08de9ae57f6ff17459cefd9e38e82d3e7aaa544bc49503b6fdaaf2c800
+F src/where.c c51ebd505c8417285ca1db8f94933a12224bf636ad93f27d821c07f93d59c035
 F src/whereInt.h 4a296fd4fa79fdcbc2b5e8c1b898901617655811223e1082b899c23ecb092217
 F src/wherecode.c 7efa97f4dc2f95548611deba68f0210ab357725899a9bae5391a525e48271875
 F src/whereexpr.c 39b6a538804c6e1248c22b33e09d00f89ae6a099c849c4d841ce3995562287b4
@@ -1852,7 +1852,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 0457e7d1961ab1f63e31d9028a9064a895f5c3fcfb56ba25e4f37e90197e3a9f
-R dfec9545ec065160dafed7d961680e93
+P 1fa29a5f2a89b6a1ee067f9cb86de1b66455126349efe3502599fc7ad224170c
+R 1705b0f74ba75d9e6c5b4546a5dce87c
 U drh
-Z 42480cb067277792c63c10d88dc25575
+Z 019e789a4ccea6f1cebc90f58acb2b95
diff --git a/manifest.uuid b/manifest.uuid
index 296a32e681..7cf6dbdda4 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-1fa29a5f2a89b6a1ee067f9cb86de1b66455126349efe3502599fc7ad224170c
\ No newline at end of file
+840de36df1aaeb4bad9a7c18e97cc560ba3b8c629c4520a05bc456d67b3347b9
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index 347598abc8..6a05d0c4da 100644
--- a/src/where.c
+++ b/src/where.c
@@ -979,18 +979,13 @@ static sqlite3_index_info *allocateIndexInfo(
     testcase( pTerm->eOperator & WO_ALL );
     if( (pTerm->eOperator & ~(WO_EQUIV))==0 ) continue;
     if( pTerm->wtFlags & TERM_VNULL ) continue;
+
+    /* tag-20191211-002: WHERE-clause constraints are not useful to the
+    ** right-hand table of a LEFT JOIN.  See tag-20191211-001 for the
+    ** equivalent restriction for ordinary tables. */
     if( (pSrc->fg.jointype & JT_LEFT)!=0
      && !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
-     && (pTerm->eOperator & (WO_IS|WO_ISNULL))
     ){
-      /* An "IS" term in the WHERE clause where the virtual table is the rhs
-      ** of a LEFT JOIN. Do not pass this term to the virtual table
-      ** implementation, as this can lead to incorrect results from SQL such
-      ** as:
-      **
-      **   "LEFT JOIN vtab WHERE vtab.col IS NULL"  */
-      testcase( pTerm->eOperator & WO_ISNULL );
-      testcase( pTerm->eOperator & WO_IS );
       continue;
     }
     assert( pTerm->u.leftColumn>=(-1) );
@@ -2472,9 +2467,9 @@ static int whereLoopAddBtreeIndex(
     ** to mix with a lower range bound from some other source */
     if( pTerm->wtFlags & TERM_LIKEOPT && pTerm->eOperator==WO_LT ) continue;
 
-    /* Do not allow constraints from the WHERE clause to be used by the
-    ** right table of a LEFT JOIN.  Only constraints in the ON clause are
-    ** allowed */
+    /* tag-20191211-001:  Do not allow constraints from the WHERE clause to
+    ** be used by the right table of a LEFT JOIN.  Only constraints in the
+    ** ON clause are allowed.  See tag-20191211-002 for the vtab equivalent. */
     if( (pSrc->fg.jointype & JT_LEFT)!=0
      && !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
     ){
-- 
2.47.2