inheritance-rowmark-ctid-fix_PG12.patch

diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index 252b8dab60..83f0954ee5 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -7190,6 +7190,95 @@ select * from bar where f1 in (select f1 from foo) for share;
   4 | 44
 (4 rows)
 
+-- Now check SELECT FOR UPDATE/SHARE with an inherited source table,
+-- where the parent is itself a foreign table
+create table loct4 (f1 int, f2 int, f3 int);
+create foreign table foo2child (f3 int) inherits (foo2)
+  server loopback options (table_name 'loct4');
+NOTICE:  moving and merging column "f3" with inherited definition
+DETAIL:  User-specified column moved to the position of the inherited column.
+explain (verbose, costs off)
+select * from bar where f1 in (select f1 from foo2) for share;
+                                      QUERY PLAN                                       
+---------------------------------------------------------------------------------------
+ LockRows
+   Output: bar.f1, bar.f2, bar.ctid, foo2.*, bar.*, bar.tableoid, foo2.tableoid
+   ->  Hash Join
+         Output: bar.f1, bar.f2, bar.ctid, foo2.*, bar.*, bar.tableoid, foo2.tableoid
+         Inner Unique: true
+         Hash Cond: (bar.f1 = foo2.f1)
+         ->  Append
+               ->  Seq Scan on public.bar
+                     Output: bar.f1, bar.f2, bar.ctid, bar.*, bar.tableoid
+               ->  Foreign Scan on public.bar2
+                     Output: bar2.f1, bar2.f2, bar2.ctid, bar2.*, bar2.tableoid
+                     Remote SQL: SELECT f1, f2, f3, ctid FROM public.loct2 FOR SHARE
+         ->  Hash
+               Output: foo2.*, foo2.f1, foo2.tableoid
+               ->  HashAggregate
+                     Output: foo2.*, foo2.f1, foo2.tableoid
+                     Group Key: foo2.f1
+                     ->  Append
+                           ->  Foreign Scan on public.foo2
+                                 Output: foo2.*, foo2.f1, foo2.tableoid
+                                 Remote SQL: SELECT f1, f2, f3 FROM public.loct1
+                           ->  Foreign Scan on public.foo2child
+                                 Output: foo2child.*, foo2child.f1, foo2child.tableoid
+                                 Remote SQL: SELECT f1, f2, f3 FROM public.loct4
+(24 rows)
+
+select * from bar where f1 in (select f1 from foo2) for share;
+ f1 | f2 
+----+----
+  2 | 22
+  4 | 44
+(2 rows)
+
+-- And with a local child relation of the foreign table parent
+create table foo2child2 (f3 int) inherits (foo2);
+NOTICE:  moving and merging column "f3" with inherited definition
+DETAIL:  User-specified column moved to the position of the inherited column.
+explain (verbose, costs off)
+select * from bar where f1 in (select f1 from foo2) for share;
+                                                QUERY PLAN                                                 
+-----------------------------------------------------------------------------------------------------------
+ LockRows
+   Output: bar.f1, bar.f2, bar.ctid, foo2.*, bar.*, bar.tableoid, foo2.ctid, foo2.tableoid
+   ->  Hash Join
+         Output: bar.f1, bar.f2, bar.ctid, foo2.*, bar.*, bar.tableoid, foo2.ctid, foo2.tableoid
+         Inner Unique: true
+         Hash Cond: (bar.f1 = foo2.f1)
+         ->  Append
+               ->  Seq Scan on public.bar
+                     Output: bar.f1, bar.f2, bar.ctid, bar.*, bar.tableoid
+               ->  Foreign Scan on public.bar2
+                     Output: bar2.f1, bar2.f2, bar2.ctid, bar2.*, bar2.tableoid
+                     Remote SQL: SELECT f1, f2, f3, ctid FROM public.loct2 FOR SHARE
+         ->  Hash
+               Output: foo2.*, foo2.f1, foo2.ctid, foo2.tableoid
+               ->  HashAggregate
+                     Output: foo2.*, foo2.f1, foo2.ctid, foo2.tableoid
+                     Group Key: foo2.f1
+                     ->  Append
+                           ->  Foreign Scan on public.foo2
+                                 Output: foo2.*, foo2.f1, foo2.ctid, foo2.tableoid
+                                 Remote SQL: SELECT f1, f2, f3, ctid FROM public.loct1
+                           ->  Foreign Scan on public.foo2child
+                                 Output: foo2child.*, foo2child.f1, foo2child.ctid, foo2child.tableoid
+                                 Remote SQL: SELECT f1, f2, f3, ctid FROM public.loct4
+                           ->  Seq Scan on public.foo2child2
+                                 Output: foo2child2.*, foo2child2.f1, foo2child2.ctid, foo2child2.tableoid
+(26 rows)
+
+select * from bar where f1 in (select f1 from foo2) for share;
+ f1 | f2 
+----+----
+  2 | 22
+  4 | 44
+(2 rows)
+
+alter table foo2child no inherit foo2;
+alter table foo2child2 no inherit foo2;
 -- Check UPDATE with inherited target and an inherited source table
 explain (verbose, costs off)
 update bar set f2 = f2 + 100 where f1 in (select f1 from foo);
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index a957ef1b1d..88c343295a 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -1834,6 +1834,26 @@ explain (verbose, costs off)
 select * from bar where f1 in (select f1 from foo) for share;
 select * from bar where f1 in (select f1 from foo) for share;
 
+-- Now check SELECT FOR UPDATE/SHARE with an inherited source table,
+-- where the parent is itself a foreign table
+create table loct4 (f1 int, f2 int, f3 int);
+create foreign table foo2child (f3 int) inherits (foo2)
+  server loopback options (table_name 'loct4');
+
+explain (verbose, costs off)
+select * from bar where f1 in (select f1 from foo2) for share;
+select * from bar where f1 in (select f1 from foo2) for share;
+
+-- And with a local child relation of the foreign table parent
+create table foo2child2 (f3 int) inherits (foo2);
+
+explain (verbose, costs off)
+select * from bar where f1 in (select f1 from foo2) for share;
+select * from bar where f1 in (select f1 from foo2) for share;
+
+alter table foo2child no inherit foo2;
+alter table foo2child2 no inherit foo2;
+
 -- Check UPDATE with inherited target and an inherited source table
 explain (verbose, costs off)
 update bar set f2 = f2 + 100 where f1 in (select f1 from foo);
diff --git a/src/backend/optimizer/util/inherit.c b/src/backend/optimizer/util/inherit.c
index f0953475b1..ad0e91e2c5 100644
--- a/src/backend/optimizer/util/inherit.c
+++ b/src/backend/optimizer/util/inherit.c
@@ -231,9 +231,25 @@ expand_inherited_rtentry(PlannerInfo *root, RelOptInfo *rel,
 		char		resname[32];
 		List	   *newvars = NIL;
 
-		/* The old PlanRowMark should already have necessitated adding TID */
-		Assert(old_allMarkTypes & ~(1 << ROW_MARK_COPY));
-
+		/* Add TID if needed, unless we had it already */
+		if (new_allMarkTypes & ~(1 << ROW_MARK_COPY) &&
+			!(old_allMarkTypes & ~(1 << ROW_MARK_COPY)))
+		{
+			/* Need to fetch TID */
+			var = makeVar(oldrc->rti,
+						  SelfItemPointerAttributeNumber,
+						  TIDOID,
+						  -1,
+						  InvalidOid,
+						  0);
+			snprintf(resname, sizeof(resname), "ctid%u", oldrc->rowmarkId);
+			tle = makeTargetEntry((Expr *) var,
+								  list_length(root->processed_tlist) + 1,
+								  pstrdup(resname),
+								  true);
+			root->processed_tlist = lappend(root->processed_tlist, tle);
+			newvars = lappend(newvars, var);
+		}
 		/* Add whole-row junk Var if needed, unless we had it already */
 		if ((new_allMarkTypes & (1 << ROW_MARK_COPY)) &&
 			!(old_allMarkTypes & (1 << ROW_MARK_COPY)))