Ooops ... make_outerjoininfo wasn't actually enforcing the join order

tglsfdc · tglsfdc · commit fdd48b185288 · 2009-05-07T20:13:09.000Z
restrictions specified for semijoins in optimizer/README, to wit that
you can't reassociate outer joins into or out of the RHS of a semijoin.
Per report from Heikki.
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.152 2009/05/06 20:31:18 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.153 2009/05/07 20:13:09 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -654,7 +654,8 @@ make_outerjoininfo(PlannerInfo *root,
 		 * lower join's RHS and the lower OJ's join condition is strict, we
 		 * can interchange the ordering of the two OJs; otherwise we must add
 		 * lower OJ's full syntactic relset to min_righthand.  Here, we must
-		 * preserve ordering anyway if the lower OJ is an antijoin.
+		 * preserve ordering anyway if either the current join is a semijoin,
+		 * or the lower OJ is an antijoin.
 		 *
 		 * Here, we have to consider that "our join condition" includes any
 		 * clauses that syntactically appeared above the lower OJ and below
@@ -670,6 +671,7 @@ make_outerjoininfo(PlannerInfo *root,
 		if (bms_overlap(right_rels, otherinfo->syn_righthand))
 		{
 			if (bms_overlap(clause_relids, otherinfo->syn_righthand) ||
+				jointype == JOIN_SEMI ||
 				otherinfo->jointype == JOIN_ANTI ||
 				!otherinfo->lhs_strict || otherinfo->delay_upper_joins)
 			{

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.152 2009/05/06 20:31:18 tgl Exp $`
	`11`	`+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.153 2009/05/07 20:13:09 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -654,7 +654,8 @@ make_outerjoininfo(PlannerInfo *root,`
`654`	`654`	`* lower join's RHS and the lower OJ's join condition is strict, we`
`655`	`655`	`* can interchange the ordering of the two OJs; otherwise we must add`
`656`	`656`	`* lower OJ's full syntactic relset to min_righthand. Here, we must`
`657`		`- * preserve ordering anyway if the lower OJ is an antijoin.`
	`657`	`+ * preserve ordering anyway if either the current join is a semijoin,`
	`658`	`+ * or the lower OJ is an antijoin.`
`658`	`659`	`*`
`659`	`660`	`* Here, we have to consider that "our join condition" includes any`
`660`	`661`	`* clauses that syntactically appeared above the lower OJ and below`
`@@ -670,6 +671,7 @@ make_outerjoininfo(PlannerInfo *root,`
`670`	`671`	`if (bms_overlap(right_rels, otherinfo->syn_righthand))`
`671`	`672`	`{`
`672`	`673`	`if (bms_overlap(clause_relids, otherinfo->syn_righthand) \|\|`
	`674`	`+ jointype == JOIN_SEMI \|\|`
`673`	`675`	`otherinfo->jointype == JOIN_ANTI \|\|`
`674`	`676`	`!otherinfo->lhs_strict \|\| otherinfo->delay_upper_joins)`
`675`	`677`	`{`