New restriction on the push-down optimization to prevent an ON or USING clause

on the left side of a RIGHT JOIN from being pushed down into a subquery that
is on the right side of that RIGHT JOIN.
[forum:/forumpost/a7d4be7fb6|Forum post a7d4be7fb6].
Also add comments to describe previously undocumented push-down optimization
restrictions.

FossilOrigin-Name: da3fba18742b6e0bd5290bee9d86a2d5cb1ff2de25d737ef93060d7c1143273f

diff --git a/manifest b/manifest
index aa696c474cf13540583928b2a45ed017d5e30906..98b1d74c099972fe6e940ca69e1c1fdac56ed6e0 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sbug\sin\sfall-back\slogic\sof\sCLI\s.clone
-D 2023-05-10T00:20:42.067
+C New\srestriction\son\sthe\spush-down\soptimization\sto\sprevent\san\sON\sor\sUSING\sclause\non\sthe\sleft\sside\sof\sa\sRIGHT\sJOIN\sfrom\sbeing\spushed\sdown\sinto\sa\ssubquery\sthat\nis\son\sthe\sright\sside\sof\sthat\sRIGHT\sJOIN.\n[forum:/forumpost/a7d4be7fb6|Forum\spost\sa7d4be7fb6].\nAlso\sadd\scomments\sto\sdescribe\spreviously\sundocumented\spush-down\soptimization\nrestrictions.
+D 2023-05-10T00:33:21.611
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -635,7 +635,7 @@ F src/printf.c b9320cdbeca0b336c3f139fd36dd121e4167dd62b35fbe9ccaa9bab44c0af38d
 F src/random.c 606b00941a1d7dd09c381d3279a058d771f406c5213c9932bbd93d5587be4b9c
 F src/resolve.c 3e53e02ce87c9582bd7e7d22f13f4094a271678d9dc72820fa257a2abb5e4032
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
-F src/select.c f9333ef8181192c22662f5cb8d257efc4a2880f9ee4853c6c4616f783d27e1b5
+F src/select.c 74cc112615f42f6dac0ecb4f4b7d2d33f89703c6b63a2a2cc88d4fba138e53f3
 F src/shell.c.in 8cfc51a5711df05ea0e8a4fbbe20117eb629233f0e92ebea21c2e7dc717ec3d9
 F src/sqlite.h.in 27ca1d4b2eda8feee468af5735182390e8fe4696522751eec0136d17323201ad
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
@@ -1407,7 +1407,7 @@ F test/printf.test 512152dca7f2f578f045a5a732e7bee08e4f47a8a212f83ce46791b518eba
 F test/printf2.test 3f55c1871a5a65507416076f6eb97e738d5210aeda7595a74ee895f2224cce60
 F test/progress.test ebab27f670bd0d4eb9d20d49cef96e68141d92fb
 F test/ptrchng.test ef1aa72d6cf35a2bbd0869a649b744e9d84977fc
-F test/pushdown.test c183fa51f93bb3a604eee9141133e36b5fbef0aac3b0447e464d977a84d6d00a
+F test/pushdown.test 043e69055d841f5c4be0ff264b2a9de32d2342c3d71b20a786b0e6656603c66a
 F test/queryonly.test 5f653159e0f552f0552d43259890c1089391dcca
 F test/quick.test 1681febc928d686362d50057c642f77a02c62e57
 F test/quickcheck.test f86b25b33455af0189b4d3fe7bd6e553115e80b2d7ec9bbe9a6b37fce0881bfe
@@ -2068,8 +2068,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 4ffae48e831eedf8f5e61dc6d38817c0fdccfb2f4f1189d07f9722b9e3a48b5e
-R eadcd86a7c963c3ce404937ef7af1e62
-U larrybr
-Z 49d92c10f87c494a6ab4dda4d8eae4e2
+P 0dcd9785c11e33e6393b7c1be1ff8fe7129f280439aed12de22d4687609a8bac
+R 3d961b43f90341a00d01bb4735ebf2fe
+U drh
+Z f03efd73d88947aad78bab321f78e97e
 # Remove this line to create a well-formed Fossil manifest.

diff --git a/manifest.uuid b/manifest.uuid
index a511499001e754a08d9f06793815509a6c69c002..26bfdb0a114f8167e834bd50944631f77248a782 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-0dcd9785c11e33e6393b7c1be1ff8fe7129f280439aed12de22d4687609a8bac
\ No newline at end of file
+da3fba18742b6e0bd5290bee9d86a2d5cb1ff2de25d737ef93060d7c1143273f
\ No newline at end of file

diff --git a/src/select.c b/src/select.c
index 6be3b6a556cdc95c22c88a66538025d319cbf6ce..079158b4dd5ef67531047a88dd7b4da6502aa059 100644 (file)
--- a/src/select.c
+++ b/src/select.c
@@ -5107,6 +5107,23 @@ static int pushDownWindowCheck(Parse *pParse, Select *pSubq, Expr *pExpr){
 **       or EXCEPT, then all of the result set columns for all arms of
 **       the compound must use the BINARY collating sequence.
 **
+**   (9) All three of the following are true:
+**
+**       (9a) The WHERE clause expression originates in the ON or USING clause
+**            of a join (either an INNER or an OUTER join), and
+**
+**       (9b) The subquery is to the right of the ON/USING clause
+**
+**       (9c) There is a RIGHT JOIN (or FULL JOIN) in between the ON/USING
+**            clause and the subquery.
+**
+**       Without this restriction, the push-down optimization might move
+**       the ON/USING filter expression from the left side of a RIGHT JOIN
+**       over to the right side, which leads to incorrect answers.
+**
+**  (10) The inner query is not the right-hand table of a RIGHT JOIN.
+**
+**  (11) The subquery is not a VALUES clause
 **
 ** Return 0 if no changes are made and non-zero if one or more WHERE clause
 ** terms are duplicated into the subquery.
@@ -5115,13 +5132,20 @@ static int pushDownWhereTerms(
   Parse *pParse,        /* Parse context (for malloc() and error reporting) */
   Select *pSubq,        /* The subquery whose WHERE clause is to be augmented */
   Expr *pWhere,         /* The WHERE clause of the outer query */
-  SrcItem *pSrc         /* The subquery term of the outer FROM clause */
+  SrcList *pSrcList,    /* The complete from clause of the outer query */
+  int iSrc              /* Which FROM clause term to try to push into  */
 ){
   Expr *pNew;
+  SrcItem *pSrc;        /* The subquery FROM term into which WHERE is pushed */
   int nChng = 0;
+  pSrc = &pSrcList->a[iSrc];
   if( pWhere==0 ) return 0;
-  if( pSubq->selFlags & (SF_Recursive|SF_MultiPart) ) return 0;
-  if( pSrc->fg.jointype & (JT_LTORJ|JT_RIGHT) ) return 0;
+  if( pSubq->selFlags & (SF_Recursive|SF_MultiPart) ){
+    return 0;           /* restrictions (2) and (11) */
+  }
+  if( pSrc->fg.jointype & (JT_LTORJ|JT_RIGHT) ){
+    return 0;           /* restrictions (10) */
+  }
 
   if( pSubq->pPrior ){
     Select *pSel;
@@ -5176,10 +5200,28 @@ static int pushDownWhereTerms(
     return 0; /* restriction (3) */
   }
   while( pWhere->op==TK_AND ){
-    nChng += pushDownWhereTerms(pParse, pSubq, pWhere->pRight, pSrc);
+    nChng += pushDownWhereTerms(pParse, pSubq, pWhere->pRight, pSrcList, iSrc);
     pWhere = pWhere->pLeft;
   }
 
+  if( ExprHasProperty(pWhere, EP_OuterON|EP_InnerON) /* (9a) */
+   && (pSrcList->a[0].fg.jointype & JT_LTORJ)!=0     /* Fast pre-test of (9c) */
+  ){
+    int jj;
+    for(jj=0; jj<iSrc; jj++){
+      if( pWhere->w.iJoin==pSrcList->a[jj].iCursor ){
+        /* If we reach this point, both (9a) and (9b) are satisfied.
+        ** The following loop checks (9c):
+        */
+        for(jj++; jj<iSrc; jj++){
+          if( (pSrcList->a[jj].fg.jointype & JT_RIGHT)!=0 ){
+            return 0;  /* restriction (9) */
+          }
+        }
+      }
+    }
+  }
+
 #if 0  /* Legacy code. Checks now done by sqlite3ExprIsTableConstraint() */
   if( isLeftJoin
    && (ExprHasProperty(pWhere,EP_OuterON)==0
@@ -7389,7 +7431,7 @@ int sqlite3Select(
     if( OptimizationEnabled(db, SQLITE_PushDown)
      && (pItem->fg.isCte==0 
          || (pItem->u2.pCteUse->eM10d!=M10d_Yes && pItem->u2.pCteUse->nUse<2))
-     && pushDownWhereTerms(pParse, pSub, p->pWhere, pItem)
+     && pushDownWhereTerms(pParse, pSub, p->pWhere, pTabList, i)
     ){
 #if TREETRACE_ENABLED
       if( sqlite3TreeTrace & 0x4000 ){

diff --git a/test/pushdown.test b/test/pushdown.test
index b9ee48c4ac9c325edf5c76e09b944e9c979303b4..2b5b1cb994e984286a86dd2ca3c67068b5dd801b 100644 (file)
--- a/test/pushdown.test
+++ b/test/pushdown.test
@@ -184,4 +184,27 @@ do_eqp_test 3.8 {
 # The query should be converted into:
 #   SELECT (SELECT count(*) FROM t1)+(SELECT count(*) FROM t2)
 
+# 2023-05-09 https://sqlite.org/forum/forumpost/a7d4be7fb6
+# Restriction (9) on the push-down optimization.
+# 
+reset_db
+db null -
+do_execsql_test 4.1 {
+  CREATE TABLE t1(a INT);
+  CREATE TABLE t2(b INT);
+  CREATE TABLE t3(c INT);
+  INSERT INTO t3(c) VALUES(3);
+  CREATE TABLE t4(d INT);
+  CREATE TABLE t5(e INT);
+  INSERT INTO t5(e) VALUES(5);
+  CREATE VIEW v6(f,g) AS SELECT d, e FROM t4 RIGHT JOIN t5 ON true;
+  SELECT * FROM  t1 JOIN t2 ON false RIGHT JOIN t3 ON true CROSS JOIN v6;
+} {- - 3 - 5}
+do_execsql_test 4.2 {
+  SELECT * FROM v6 JOIN t5 ON false RIGHT JOIN t3 ON true;
+} {- - - 3}
+do_execsql_test 4.3 {
+  SELECT * FROM t1 JOIN t2 ON false JOIN v6 ON true RIGHT JOIN t3 ON true;
+} {- - - - 3}
+
 finish_test