Disallow NAMEDTUPLESTORE RTEs in stored views, rules, etc.

A named tuplestore is necessarily a transient object, so it makes
no sense to reference one in a persistent object such as a view.
We didn't previously prevent that, with the result that if you
tried you would get some weird failure about how the executor
couldn't find the tuplestore.

We can mechanize a check for this case cheaply by making dependency
extraction complain if it comes across such an RTE.  This is a
plausible way of dealing with it since part of the problem is that we
have no way to make a pg_depend representation of a named tuplestore.

Report and fix by Yugo Nagata.  Although this is an old problem,
it's a very weird corner case and there have been no reports from
end users.  So it seems sufficient to fix it in master.

Discussion: https://postgr.es/m/20240726160714.e74d0db579f2c017e1ca0b7e@sraoss.co.jp

3 files changed, 54 insertions, 0 deletions

diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index 096b68c7f39..18316a3968b 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -2191,7 +2191,22 @@ find_expr_references_walker(Node *node,
 					}
 					context->rtables = list_delete_first(context->rtables);
 					break;
+				case RTE_NAMEDTUPLESTORE:
+
+					/*
+					 * Cataloged objects cannot depend on tuplestores, because
+					 * those have no cataloged representation.  For now we can
+					 * call the tuplestore a "transition table" because that's
+					 * the only kind exposed to SQL, but someday we might have
+					 * to work harder.
+					 */
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("transition table \"%s\" cannot be referenced in a persistent object",
+									rte->eref->aliasname)));
+					break;
 				default:
+					/* Other RTE types can be ignored here */
 					break;
 			}
 		}
diff --git a/src/test/regress/expected/triggers.out b/src/test/regress/expected/triggers.out
index a044d6afe27..0657da17577 100644
--- a/src/test/regress/expected/triggers.out
+++ b/src/test/regress/expected/triggers.out
@@ -3315,6 +3315,26 @@ create trigger my_table_col_update_trig
 ERROR:  transition tables cannot be specified for triggers with column lists
 drop table my_table;
 --
+-- Verify that transition tables can't be used in, eg, a view.
+--
+create table my_table (a int);
+create function make_bogus_matview() returns trigger as
+$$ begin
+  create materialized view transition_test_mv as select * from new_table;
+  return new;
+end $$
+language plpgsql;
+create trigger make_bogus_matview
+  after insert on my_table
+  referencing new table as new_table
+  for each statement execute function make_bogus_matview();
+insert into my_table values (42);  -- error
+ERROR:  transition table "new_table" cannot be referenced in a persistent object
+CONTEXT:  SQL statement "create materialized view transition_test_mv as select * from new_table"
+PL/pgSQL function make_bogus_matview() line 2 at SQL statement
+drop table my_table;
+drop function make_bogus_matview();
+--
 -- Test firing of triggers with transition tables by foreign key cascades
 --
 create table refd_table (a int primary key, b text);
diff --git a/src/test/regress/sql/triggers.sql b/src/test/regress/sql/triggers.sql
index 51610788b21..7e2f7597c10 100644
--- a/src/test/regress/sql/triggers.sql
+++ b/src/test/regress/sql/triggers.sql
@@ -2435,6 +2435,25 @@ create trigger my_table_col_update_trig
 drop table my_table;
 
 --
+-- Verify that transition tables can't be used in, eg, a view.
+--
+
+create table my_table (a int);
+create function make_bogus_matview() returns trigger as
+$$ begin
+  create materialized view transition_test_mv as select * from new_table;
+  return new;
+end $$
+language plpgsql;
+create trigger make_bogus_matview
+  after insert on my_table
+  referencing new table as new_table
+  for each statement execute function make_bogus_matview();
+insert into my_table values (42);  -- error
+drop table my_table;
+drop function make_bogus_matview();
+
+--
 -- Test firing of triggers with transition tables by foreign key cascades
 --