From: dan <Dan Kennedy>
Date: Tue, 25 Apr 2023 14:37:12 +0000 (+0000)
Subject: Avoid assuming that an expression in an ON() clause that evaluates to zero implies... 
X-Git-Tag: version-3.42.0~95
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0941ea8a62991ab5725ff729fd4d8cacce1434e1;p=thirdparty%2Fsqlite.git

Avoid assuming that an expression in an ON() clause that evaluates to zero implies that the query will return zero rows when the query contains a RIGHT JOIN. [forum:95849acbe1|Forum Post 95849acbe1].

FossilOrigin-Name: 1783655ea422185e75593b89e4ef452a6f5496aefd389f88ce7fe4b7d41d6a98
---

diff --git a/manifest b/manifest
index 3fc806927c..39088ebefe 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Handle\snewline-trimmed\sinput\sTEXT\scorrectly\sin\sbase64,\sbase85\sUDFs.
-D 2023-04-25T04:28:39.874
+C Avoid\sassuming\sthat\san\sexpression\sin\san\sON()\sclause\sthat\sevaluates\sto\szero\simplies\sthat\sthe\squery\swill\sreturn\szero\srows\swhen\sthe\squery\scontains\sa\sRIGHT\sJOIN.\s[forum:95849acbe1|Forum\sPost\s95849acbe1].
+D 2023-04-25T14:37:12.443
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -717,7 +717,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 3f4ac276a60bda76f9f1f6f1c2c38599bacd4987e5efcd3f7fed2647bf97280a
 F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
 F src/walker.c f890a3298418d7cba3b69b8803594fdc484ea241206a8dfa99db6dd36f8cbb3b
-F src/where.c ef9e644d1d76e86f68c941eb05d30a98fc0811eeef2a110906d81fedde81b6bf
+F src/where.c 8899e22a397c839f551c8e1741c100ae2675feb0fe0a383d55816f2ca3d2b583
 F src/whereInt.h e25203e5bfee149f5f1225ae0166cfb4f1e65490c998a024249e98bb0647377c
 F src/wherecode.c 85790d7e5365ac41085713331ce52e4343586ad3d37d218ffe00572357baa62b
 F src/whereexpr.c 1dfda1695e4480c24248157df55bb4d66c732dc8d14ac16b4f076bb15de93d63
@@ -1242,7 +1242,7 @@ F test/joinC.test 1f1a602c2127f55f136e2cbd3bf2d26546614bf8cffe5902ec1ac9c07f87f2
 F test/joinD.test 2ce62e7353a0702ca5e70008faf319c1d4686aa19fba34275c6d1da0e960be28
 F test/joinE.test d5d182f3812771e2c0d97c9dcf5dbe4c41c8e21c82560e59358731c4a3981d6b
 F test/joinF.test 53dd66158806823ea680dd7543b5406af151b5aafa5cd06a7f3231cd94938127
-F test/joinH.test 15f501b33d848521964afde9865a92aeca79c8c41fa84dc4dc3f865c9ed8c868
+F test/joinH.test 705157cf9b9b7c207caf960812a7d0e4dc1dd45aa5fb2b563f12df59088645f3
 F test/journal1.test c7b768041b7f494471531e17abc2f4f5ebf9e5096984f43ed17c4eb80ba34497
 F test/journal2.test 9dac6b4ba0ca79c3b21446bbae993a462c2397c4
 F test/journal3.test 7c3cf23ffc77db06601c1fcfc9743de8441cb77db9d1aa931863d94f5ffa140e
@@ -2059,8 +2059,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P e6f9c0b1f963033a8e17d13935c5c6b12d263fe10c585035a3d1f1154c6ba5d6
-R 7500f54b9a757a6bdf9e41121051af70
-U larrybr
-Z e45f0a7f30148e18d14433c2a4564a3c
+P 8f637aae23e6638c064a34262dcf16a3cdfd000fb1fa1b2a834b292fe6659408
+R 162170fabcf6c22e465922e65b3136a8
+U dan
+Z 748c21dff95a1a525519cd6fda798ed3
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index a40e09b2de..b242eaaebc 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-8f637aae23e6638c064a34262dcf16a3cdfd000fb1fa1b2a834b292fe6659408
\ No newline at end of file
+1783655ea422185e75593b89e4ef452a6f5496aefd389f88ce7fe4b7d41d6a98
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index 8200daca80..bc63c53b58 100644
--- a/src/where.c
+++ b/src/where.c
@@ -5982,22 +5982,46 @@ WhereInfo *sqlite3WhereBegin(
   }
   if( pParse->nErr ) goto whereBeginError;
 
-  /* Special case: WHERE terms that do not refer to any tables in the join
-  ** (constant expressions). Evaluate each such term, and jump over all the
-  ** generated code if the result is not true.  
+  /* The False-WHERE-Term-Bypass optimization:
   **
-  ** Do not do this if the expression contains non-deterministic functions
-  ** that are not within a sub-select. This is not strictly required, but
-  ** preserves SQLite's legacy behaviour in the following two cases:
+  ** If there are WHERE terms that are false, then no rows will be output,
+  ** so skip over all of the code generated here.
   **
-  **   FROM ... WHERE random()>0;           -- eval random() once per row
-  **   FROM ... WHERE (SELECT random())>0;  -- eval random() once overall
+  ** Conditions:
+  **
+  **   (1)  The WHERE term must not refer to any tables in the join.
+  **   (2)  The term must not come from an ON clause on the
+  **        right-hand side of a LEFT or FULL JOIN.
+  **   (3)  The term must not come from an ON clause, or there must be
+  **        no RIGHT or FULL OUTER joins in pTabList.
+  **   (4)  If the expression contains non-deterministic functions
+  **        that are not within a sub-select. This is not required
+  **        for correctness but rather to preserves SQLite's legacy
+  **        behaviour in the following two cases:
+  **
+  **          WHERE random()>0;           -- eval random() once per row
+  **          WHERE (SELECT random())>0;  -- eval random() just once overall
+  **
+  ** Note that the Where term need not be a constant in order for this
+  ** optimization to apply, though it does need to be constant relative to
+  ** the current subquery (condition 1).  The term might include variables
+  ** from outer queries so that the value of the term changes from one
+  ** invocation of the current subquery to the next.
   */
   for(ii=0; ii<sWLB.pWC->nBase; ii++){
-    WhereTerm *pT = &sWLB.pWC->a[ii];
+    WhereTerm *pT = &sWLB.pWC->a[ii];  /* A term of the WHERE clause */
+    Expr *pX;                          /* The expression of pT */
+    int ltoj;                          /* Left table of the join */
     if( pT->wtFlags & TERM_VIRTUAL ) continue;
-    if( pT->prereqAll==0 && (nTabList==0 || exprIsDeterministic(pT->pExpr)) ){
-      sqlite3ExprIfFalse(pParse, pT->pExpr, pWInfo->iBreak, SQLITE_JUMPIFNULL);
+    pX = pT->pExpr;
+    assert( pX!=0 );
+    assert( pT->prereqAll!=0 || !ExprHasProperty(pX, EP_OuterON) );
+    if( pT->prereqAll==0                           /* Conditions (1) and (2) */
+     && (nTabList==0 || exprIsDeterministic(pX))   /* Condition (4) */
+     && !(ExprHasProperty(pX, EP_InnerON)          /* Condition (3) */
+          && (pTabList->a[0].fg.jointype & JT_LTORJ)!=0 )
+    ){
+      sqlite3ExprIfFalse(pParse, pX, pWInfo->iBreak, SQLITE_JUMPIFNULL);
       pT->wtFlags |= TERM_CODED;
     }
   }
diff --git a/test/joinH.test b/test/joinH.test
index 1d5f66afa2..78d1556293 100644
--- a/test/joinH.test
+++ b/test/joinH.test
@@ -89,5 +89,35 @@ do_execsql_test 4.4 {
   SELECT (d IS NULL) FROM t1 RIGHT JOIN t2 ON (j=33);
 } {1}
 
+#-------------------------------------------------------------------------
+#
+reset_db
+do_execsql_test 5.0 {
+  CREATE TABLE t0(w);
+  CREATE TABLE t1(x);
+  CREATE TABLE t2(y);
+  CREATE TABLE t3(z);
+  INSERT INTO t3 VALUES('t3val');
+}
+
+do_execsql_test 5.1 {
+  SELECT * FROM t1 INNER JOIN t2 ON (0) RIGHT OUTER JOIN t3;
+} {{} {} t3val}
+
+do_execsql_test 5.2 {
+  SELECT * FROM t1 INNER JOIN t2 ON (0) FULL OUTER JOIN t3;
+} {{} {} t3val}
+
+do_execsql_test 5.3 {
+  SELECT * FROM t3 LEFT JOIN t2 ON (0);
+} {t3val {}}
+
+do_execsql_test 5.4 {
+  SELECT * FROM t0 RIGHT JOIN t1 INNER JOIN t2 ON (0) RIGHT JOIN t3
+} {{} {} {} t3val}
+
+do_execsql_test 5.5 {
+  SELECT * FROM t0 RIGHT JOIN t1 INNER JOIN t2 ON (0)
+} {}
 
 finish_test