Fix create_lateral_join_info to handle dead relations properly.

Commit 0a480502b0 broke it.

Report by Andreas Seltenreich.  Fix by Ashutosh Bapat.

Discussion: http://postgr.es/m/874ls2vrnx.fsf@ansel.ydns.eu

src/backend/optimizer/plan/initsplan.c

@@ -632,7 +632,11 @@ create_lateral_join_info(PlannerInfo *root)
 		RelOptInfo *brel = root->simple_rel_array[rti];
 		RangeTblEntry *brte = root->simple_rte_array[rti];
 
-		if (brel == NULL)
+		/*
+		 * Skip empty slots. Also skip non-simple relations i.e. dead
+		 * relations.
+		 */
+		if (brel == NULL || !IS_SIMPLE_REL(brel))
 			continue;
 
 		/*
@@ -644,7 +648,6 @@ create_lateral_join_info(PlannerInfo *root)
 		 * therefore be marked with the appropriate lateral info so that those
 		 * children eventually get marked also.
 		 */
-		Assert(IS_SIMPLE_REL(brel));
 		Assert(brte);
 		if (brel->reloptkind == RELOPT_OTHER_MEMBER_REL &&
 			(brte->rtekind != RTE_RELATION ||

src/test/regress/expected/join.out

@@ -4060,6 +4060,18 @@ select i8.* from int8_tbl i8 left join (select f1 from int4_tbl group by f1) i4
  Seq Scan on int8_tbl i8
 (1 row)
 
+-- check join removal with lateral references
+explain (costs off)
+select 1 from (select a.id FROM a left join b on a.b_id = b.id) q,
+			  lateral generate_series(1, q.id) gs(i) where q.id = gs.i;
+                QUERY PLAN                 
+-------------------------------------------
+ Nested Loop
+   ->  Seq Scan on a
+   ->  Function Scan on generate_series gs
+         Filter: (a.id = i)
+(4 rows)
+
 rollback;
 create temp table parent (k int primary key, pd int);
 create temp table child (k int unique, cd int);

src/test/regress/sql/join.sql

@@ -1336,6 +1336,11 @@ explain (costs off)
 select i8.* from int8_tbl i8 left join (select f1 from int4_tbl group by f1) i4
   on i8.q1 = i4.f1;
 
+-- check join removal with lateral references
+explain (costs off)
+select 1 from (select a.id FROM a left join b on a.b_id = b.id) q,
+			  lateral generate_series(1, q.id) gs(i) where q.id = gs.i;
+
 rollback;
 
 create temp table parent (k int primary key, pd int);