Make RelationFlushRelation() work without ResourceOwner during abort

ReorderBufferImmediateInvalidation() executes invalidation messages in
an aborted transaction. However, RelationFlushRelation sometimes
required a valid resource owner, to temporarily increment the refcount
of the relache entry. Commit b8bff07daa worked around that in the main
subtransaction abort function, AbortSubTransaction(), but missed this
similar case in ReorderBufferImmediateInvalidation().

To fix, introduce a separate function to invalidate a relcache
entry. It does the same thing as RelationClearRelation(rebuild==true)
does when outside a transaction, but can be called without
incrementing the refcount.

Add regression test. Before this fix, it failed with:

ERROR: ResourceOwnerEnlarge called after release started

Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://www.postgresql.org/message-id/e56be7d9-14b1-664d-0bfc-00ce9772721c@gmail.com

1 files changed, 27 insertions, 0 deletions

diff --git a/contrib/test_decoding/sql/decoding_in_xact.sql b/contrib/test_decoding/sql/decoding_in_xact.sql
index 108782dc2e9..233ade5b6ce 100644
--- a/contrib/test_decoding/sql/decoding_in_xact.sql
+++ b/contrib/test_decoding/sql/decoding_in_xact.sql
@@ -38,4 +38,31 @@ COMMIT;
 INSERT INTO nobarf(data) VALUES('3');
 SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
 
+-- Decoding works in transaction that issues DDL
+--
+-- We had issues handling relcache invalidations with these, see
+-- https://www.postgresql.org/message-id/e56be7d9-14b1-664d-0bfc-00ce9772721c@gmail.com
+CREATE TABLE tbl_created_outside_xact(id SERIAL PRIMARY KEY);
+BEGIN;
+  -- TRUNCATE changes the relfilenode and sends relcache invalidation
+  TRUNCATE tbl_created_outside_xact;
+  INSERT INTO tbl_created_outside_xact(id) VALUES('1');
+
+  -- don't show yet, haven't committed
+  SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+COMMIT;
+SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+
+SET debug_logical_replication_streaming = immediate;
+BEGIN;
+  CREATE TABLE tbl_created_in_xact(id SERIAL PRIMARY KEY);
+  INSERT INTO tbl_created_in_xact VALUES (1);
+
+  CHECKPOINT; -- Force WAL flush, so that the above changes will be streamed
+
+  SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'stream-changes', '1');
+COMMIT;
+RESET debug_logical_replication_streaming;
+SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+
 SELECT 'stop' FROM pg_drop_replication_slot('regression_slot');