From 4dd1a202deb6bb6411eb13a0623f4c9d0f3e0d1a Mon Sep 17 00:00:00 2001
From: drh <>
Date: Fri, 16 Jan 2026 15:53:20 +0000
Subject: [PATCH] The optimization at [8bdda827a3d26800] is incorrect for the
 case where one of the two expressions has been commuted such that the
 collating sequence has changed.  This check-in fixes the problem.  Problem
 reported by [forum:/forumpost/2026-01-16T11:35:28Z|forum post
 2026-01-16T11:35:28Z].

FossilOrigin-Name: 9d8fb7a9e23d5ef76d05824401976247debe51be6f658f132609257a068a73de
---
 manifest         | 14 +++++++-------
 manifest.uuid    |  2 +-
 src/whereexpr.c  | 16 +++++++++++-----
 test/whereK.test | 13 +++++++++++++
 4 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/manifest b/manifest
index 741cd015e3..25cf9c2b46 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Change\sthe\scopyright\son\sthe\stool/dbtotxt.c\ssource\scode\sfile\sto\sthe\nstandard\sSQLite\sblessing.
-D 2026-01-16T12:13:42.015
+C The\soptimization\sat\s[8bdda827a3d26800]\sis\sincorrect\sfor\sthe\scase\swhere\sone\nof\sthe\stwo\sexpressions\shas\sbeen\scommuted\ssuch\sthat\sthe\scollating\ssequence\nhas\schanged.\s\sThis\scheck-in\sfixes\sthe\sproblem.\s\sProblem\sreported\sby\n[forum:/forumpost/2026-01-16T11:35:28Z|forum\spost\s2026-01-16T11:35:28Z].
+D 2026-01-16T15:53:20.470
 F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@ -823,7 +823,7 @@ F src/walker.c d5006d6b005e4ea7302ad390957a8d41ed83faa177e412f89bc5600a7462a014
 F src/where.c 0079b6ba463ae806b99b20cb335729dcce5f3e496b81cccf6441dc11f8c5bf92
 F src/whereInt.h 8d94cb116c9e06205c3d5ac87af065fc044f8cf08bfdccd94b6ea1c1308e65da
 F src/wherecode.c 71c5c6804b7f882dec8ec858758accae02fcfca13df3cc720f1f258e663ec7c5
-F src/whereexpr.c 5f412da6616e26b8000dd736a5ce5da0018dff0933cd656bbb25f407db16bf93
+F src/whereexpr.c cadb37fbaa2cb6d1ec1687923c3ac21aed4187d198f4500c00a01abb24c3cb44
 F src/window.c c0a38cd32473e8e8e7bc435039f914a36ca42465506dc491c65870c01ddac9fb
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/affinity2.test 4d7a34d328e58ca2a2d78fd76c27614a41ca7ddf4312ded9c68c04f430b3b47d
@@ -2040,7 +2040,7 @@ F test/whereG.test 875d020ac0a47828b31e36c54f1bf0cf81c9ea43b257bc21286eca1fe9a48
 F test/whereH.test e4b07f7a3c2f5d31195cd33710054c78667573b2
 F test/whereI.test c4bb7e2ca56d49bd8ab5c7bd085b8b83e353922b46904d68aefb3c7468643581
 F test/whereJ.test fc05e374cc9f2dc204148d6c06822c380ad388895fe97a6d335b94a26a08aecf
-F test/whereK.test 0270ab7f04ba5436fb9156d31d642a1c82727f4c4bfe5ba90d435c78cf44684a
+F test/whereK.test 4fb96b078f2ecedc467fa53177787378ff659539e415a4256cae7ae4e2a804b2
 F test/whereL.test cb115604cc9bd61acbc99a1f1df0eb1ea7a7875a77fef25ba9282f01d10283e1
 F test/whereM.test 0dbc9998783458ddcf3cc078ca7c2951d8b2677d472ecf0028f449ed327c0250
 F test/whereN.test 63a3584b71acfb6963416de82f26c6b1644abc5ca6080c76546b9246734c8803
@@ -2192,8 +2192,8 @@ F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee
 F tool/warnings.sh d924598cf2f55a4ecbc2aeb055c10bd5f48114793e7ba25f9585435da29e7e98
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
 F tool/winmain.c 00c8fb88e365c9017db14c73d3c78af62194d9644feaf60e220ab0f411f3604c
-P a5918835e172fd4eda6511d297b61368952d617eac33950b67368671e3bd40fe
-R c602375ef72a479dcec90722a6270c60
+P 766c89e009578aa5c1a92cbb2dcc34b3529cf4dd6157f07c84f08470d81942a9
+R bdcc204a60ddb01f203734624d8fbe88
 U drh
-Z cd561f5e126a2aa4688b11fcaa2ab0b6
+Z 38e9f9ef4cf328d41d09316ce8aaeefa
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index a3bc416c01..e02e56b585 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-766c89e009578aa5c1a92cbb2dcc34b3529cf4dd6157f07c84f08470d81942a9
+9d8fb7a9e23d5ef76d05824401976247debe51be6f658f132609257a068a73de
diff --git a/src/whereexpr.c b/src/whereexpr.c
index 91386de3f6..9ee4014dc5 100644
--- a/src/whereexpr.c
+++ b/src/whereexpr.c
@@ -549,16 +549,22 @@ static void whereCombineDisjuncts(
   Expr *pNew;            /* New virtual expression */
   int op;                /* Operator for the combined expression */
   int idxNew;            /* Index in pWC of the next virtual term */
+  Expr *pA, *pB;         /* Expressions associated with pOne and pTwo */
 
   if( (pOne->wtFlags | pTwo->wtFlags) & TERM_VNULL ) return;
   if( (pOne->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
   if( (pTwo->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
   if( (eOp & (WO_EQ|WO_LT|WO_LE))!=eOp
    && (eOp & (WO_EQ|WO_GT|WO_GE))!=eOp ) return;
-  assert( pOne->pExpr->pLeft!=0 && pOne->pExpr->pRight!=0 );
-  assert( pTwo->pExpr->pLeft!=0 && pTwo->pExpr->pRight!=0 );
-  if( sqlite3ExprCompare(0,pOne->pExpr->pLeft, pTwo->pExpr->pLeft, -1) ) return;
-  if( sqlite3ExprCompare(0,pOne->pExpr->pRight, pTwo->pExpr->pRight,-1) )return;
+  pA = pOne->pExpr;
+  pB = pTwo->pExpr;
+  assert( pA->pLeft!=0 && pA->pRight!=0 );
+  assert( pB->pLeft!=0 && pB->pRight!=0 );
+  if( sqlite3ExprCompare(0,pA->pLeft, pB->pLeft, -1) )  return;
+  if( sqlite3ExprCompare(0,pA->pRight, pB->pRight,-1) ) return;
+  if( ExprHasProperty(pA,EP_Commuted)!=ExprHasProperty(pB,EP_Commuted) ){
+    return;
+  }
   /* If we reach this point, it means the two subterms can be combined */
   if( (eOp & (eOp-1))!=0 ){
     if( eOp & (WO_LT|WO_LE) ){
@@ -569,7 +575,7 @@ static void whereCombineDisjuncts(
     }
   }
   db = pWC->pWInfo->pParse->db;
-  pNew = sqlite3ExprDup(db, pOne->pExpr, 0);
+  pNew = sqlite3ExprDup(db, pA, 0);
   if( pNew==0 ) return;
   for(op=TK_EQ; eOp!=(WO_EQ<<(op-TK_EQ)); op++){ assert( op<TK_GE ); }
   pNew->op = op;
diff --git a/test/whereK.test b/test/whereK.test
index 060d470ff9..995c083712 100644
--- a/test/whereK.test
+++ b/test/whereK.test
@@ -69,4 +69,17 @@ do_execsql_test 1.5eqp {
    ORDER BY +a;
 } {/SEARCH t1 USING INDEX t1bc/}
 
+# https://sqlite.org/forum/forumpost/2026-01-16T11:35:28Z
+do_execsql_test 2.1 {
+  DROP TABLE t1;
+  CREATE TABLE t0(x COLLATE NOCASE);
+  CREATE INDEX t0x ON t0(x);
+  CREATE TABLE t1(y);
+  INSERT INTO t0 VALUES('a');
+  INSERT INTO t1 VALUES('AB');
+  SELECT count(*) FROM t0, t1 WHERE (y BETWEEN 1 AND x) OR (x>=y AND x);
+  SELECT count(*) FROM t0, t1 WHERE (x>=y AND x) OR (y BETWEEN 1 AND x);
+} {1 1}
+
+
 finish_test
-- 
2.47.3