Disable WAL-skipping optimization for COPY on views and foreign tables

COPY can skip writing WAL when loading data on a table which has been
created in the same transaction as the one loading the data, however
this cannot work on views or foreign table as this would result in
trying to flush relation files which do not exist.  So disable the
optimization so as commands are able to work the same way with any
configuration of wal_level.

Tests are added to cover the different cases, which need to have
wal_level set to minimal to allow the problem to show up, and that is
not the default configuration.

Reported-by: Luis M. Carril, Etsuro Fujita
Author: Amit Langote, Michael Paquier
Reviewed-by: Etsuro Fujita
Discussion: https://postgr.es/m/15552-c64aa14c5c22f63c@postgresql.org
Backpatch-through: 10, where support for COPY on views has been added,
while v11 has added support for COPY on foreign tables.

1 files changed, 14 insertions, 0 deletions

diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index f963e99ab63..f438165650c 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -2124,6 +2124,20 @@ drop trigger loc2_trig_row_before_insert on loc2;
 
 delete from rem2;
 
+-- test COPY FROM with foreign table created in the same transaction
+create table loc3 (f1 int, f2 text);
+begin;
+create foreign table rem3 (f1 int, f2 text)
+	server loopback options(table_name 'loc3');
+copy rem3 from stdin;
+1	foo
+2	bar
+\.
+commit;
+select * from rem3;
+drop foreign table rem3;
+drop table loc3;
+
 -- ===================================================================
 -- test IMPORT FOREIGN SCHEMA
 -- ===================================================================