Don't pass "ONLY" options specified in TRUNCATE to foreign data wrapper.

Commit 8ff1c94649 allowed TRUNCATE command to truncate foreign tables.
Previously the information about "ONLY" options specified in TRUNCATE
command were passed to the foreign data wrapper. Then postgres_fdw
constructed the TRUNCATE command to issue the remote server and
included "ONLY" options in it based on the passed information.

On the other hand, "ONLY" options specified in SELECT, UPDATE or DELETE
have no effect when accessing or modifying the remote table, i.e.,
are not passed to the foreign data wrapper. So it's inconsistent to
make only TRUNCATE command pass the "ONLY" options to the foreign data
wrapper. Therefore this commit changes the TRUNCATE command so that
it doesn't pass the "ONLY" options to the foreign data wrapper,
for the consistency with other statements. Also this commit changes
postgres_fdw so that it always doesn't include "ONLY" options in
the TRUNCATE command that it constructs.

Author: Fujii Masao
Reviewed-by: Bharath Rupireddy, Kyotaro Horiguchi, Justin Pryzby, Zhihong Yu
Discussion: https://postgr.es/m/551ed8c1-f531-818b-664a-2cecdab99cd8@oss.nttdata.com

1 files changed, 11 insertions, 5 deletions

diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 74590089bd1..dcd36a9753e 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -2355,7 +2355,6 @@ drop table loc3;
 -- test for TRUNCATE
 -- ===================================================================
 CREATE TABLE tru_rtable0 (id int primary key);
-CREATE TABLE tru_rtable1 (id int primary key);
 CREATE FOREIGN TABLE tru_ftable (id int)
        SERVER loopback OPTIONS (table_name 'tru_rtable0');
 INSERT INTO tru_rtable0 (SELECT x FROM generate_series(1,10) x);
@@ -2363,6 +2362,7 @@ INSERT INTO tru_rtable0 (SELECT x FROM generate_series(1,10) x);
 CREATE TABLE tru_ptable (id int) PARTITION BY HASH(id);
 CREATE TABLE tru_ptable__p0 PARTITION OF tru_ptable
                             FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE tru_rtable1 (id int primary key);
 CREATE FOREIGN TABLE tru_ftable__p1 PARTITION OF tru_ptable
                                     FOR VALUES WITH (MODULUS 2, REMAINDER 1)
        SERVER loopback OPTIONS (table_name 'tru_rtable1');
@@ -2428,6 +2428,8 @@ SELECT count(*) from tru_ftable; -- 0
 SELECT count(*) from tru_pk_ftable; -- 0
 
 -- truncate with ONLY clause
+-- Since ONLY is specified, the table tru_ftable_child that inherits
+-- tru_ftable_parent locally is not truncated.
 TRUNCATE ONLY tru_ftable_parent;
 SELECT sum(id) FROM tru_ftable_parent;  -- 126
 TRUNCATE tru_ftable_parent;
@@ -2439,13 +2441,17 @@ INSERT INTO tru_rtable0 (SELECT x FROM generate_series(5,9) x);
 INSERT INTO tru_rtable0_child (SELECT x FROM generate_series(10,14) x);
 SELECT sum(id) FROM tru_ftable;   -- 95
 
-TRUNCATE ONLY tru_ftable;		-- truncate only parent portion
-SELECT sum(id) FROM tru_ftable;   -- 60
+-- Both parent and child tables in the foreign server are truncated
+-- even though ONLY is specified because ONLY has no effect
+-- when truncating a foreign table.
+TRUNCATE ONLY tru_ftable;
+SELECT count(*) FROM tru_ftable;   -- 0
 
 INSERT INTO tru_rtable0 (SELECT x FROM generate_series(21,25) x);
-SELECT sum(id) FROM tru_ftable;		-- 175
+INSERT INTO tru_rtable0_child (SELECT x FROM generate_series(26,30) x);
+SELECT sum(id) FROM tru_ftable;		-- 255
 TRUNCATE tru_ftable;			-- truncate both of parent and child
-SELECT count(*) FROM tru_ftable;    -- empty
+SELECT count(*) FROM tru_ftable;    -- 0
 
 -- cleanup
 DROP FOREIGN TABLE tru_ftable_parent, tru_ftable_child, tru_pk_ftable,tru_ftable__p1,tru_ftable;