diff --git a/contrib/postgres_fdw/connection.c b/contrib/postgres_fdw/connection.c
index 8a8d3b4481f..0eb55bdfeb9 100644
--- a/contrib/postgres_fdw/connection.c
+++ b/contrib/postgres_fdw/connection.c
@@ -2111,8 +2111,8 @@ pgfdw_finish_abort_cleanup(List *pending_entries, List *cancel_requested,
/* Number of output arguments (columns) for various API versions */
#define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1 2
-#define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2 5
-#define POSTGRES_FDW_GET_CONNECTIONS_COLS 5 /* maximum of above */
+#define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2 6
+#define POSTGRES_FDW_GET_CONNECTIONS_COLS 6 /* maximum of above */
/*
* Internal function used by postgres_fdw_get_connections variants.
@@ -2128,13 +2128,16 @@ pgfdw_finish_abort_cleanup(List *pending_entries, List *cancel_requested,
*
* For API version 1.2 and later, this function takes an input parameter
* to check a connection status and returns the following
- * additional values along with the three values from version 1.1:
+ * additional values along with the four values from version 1.1:
*
* - user_name - the local user name of the active connection. In case the
* user mapping is dropped but the connection is still active, then the
* user name will be NULL in the output.
* - used_in_xact - true if the connection is used in the current transaction.
* - closed - true if the connection is closed.
+ * - remote_backend_pid - process ID of remote backend handling connection. In
+ * case the connection status is not OK or no backend assigned to this
+ * connection then remote backend pid will be NULL in the output.
*
* No records are returned when there are no cached connections at all.
*/
@@ -2261,6 +2264,7 @@ postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
if (api_version >= PGFDW_V1_2)
{
bool check_conn = PG_GETARG_BOOL(0);
+ int remote_backend_pid;
/* Is this connection used in the current transaction? */
values[i++] = BoolGetDatum(entry->xact_depth > 0);
@@ -2273,6 +2277,16 @@ postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo,
values[i++] = BoolGetDatum(pgfdw_conn_check(entry->conn) != 0);
else
nulls[i++] = true;
+
+ /*
+ * Return non-zero remote backend ID. Otherwise, return NULL to indicate
+ * connection status is not OK or no backend assigned to this connection.
+ */
+ remote_backend_pid = PQbackendPID(entry->conn);
+ if (remote_backend_pid != 0)
+ values[i++] = Int32GetDatum(remote_backend_pid);
+ else
+ nulls[i++] = true;
}
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index daa3b1d7a6d..5d4188407f4 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -10589,13 +10589,15 @@ drop cascades to foreign table ft7
-- List all the existing cached connections. loopback and loopback3
-- should be output as invalid connections. Also the server name and user name
-- for loopback3 should be NULL because both server and user mapping were
--- dropped.
-SELECT server_name, user_name = CURRENT_USER as "user_name = CURRENT_USER", valid, used_in_xact, closed
+-- dropped. remote_backend_pid will continue to return available as it fetch remote
+-- server backend pid from cached connections.
+SELECT server_name, user_name = CURRENT_USER as "user_name = CURRENT_USER", valid, used_in_xact, closed,
+CASE WHEN remote_backend_pid = ANY(SELECT pid FROM pg_stat_activity WHERE backend_type = 'client backend' AND pid <> pg_backend_pid()) then 'available' ELSE 'not available' END AS remote_backend_pid
FROM postgres_fdw_get_connections() ORDER BY 1;
- server_name | user_name = CURRENT_USER | valid | used_in_xact | closed
--------------+--------------------------+-------+--------------+--------
- loopback | t | f | t |
- | | f | t |
+ server_name | user_name = CURRENT_USER | valid | used_in_xact | closed | remote_backend_pid
+-------------+--------------------------+-------+--------------+--------+--------------------
+ loopback | t | f | t | | available
+ | | f | t | | available
(2 rows)
-- The invalid connections get closed in pgfdw_xact_callback during commit.
@@ -12436,11 +12438,12 @@ SELECT 1 FROM ft1 LIMIT 1;
-- Since the remote server is still connected, "closed" should be FALSE,
-- or NULL if the connection status check is not available.
-SELECT CASE WHEN closed IS NOT true THEN 1 ELSE 0 END
+SELECT server_name, CASE WHEN closed IS NOT true THEN 'false' ELSE 'true' END AS remote_conn_closed,
+CASE WHEN remote_backend_pid = (SELECT pid FROM pg_stat_activity WHERE application_name = 'fdw_conn_check') THEN 'available' ELSE 'not available' END AS remote_backend_pid
FROM postgres_fdw_get_connections(true);
- case
-------
- 1
+ server_name | remote_conn_closed | remote_backend_pid
+-------------+--------------------+--------------------
+ loopback | false | available
(1 row)
-- After terminating the remote backend, since the connection is closed,
@@ -12450,11 +12453,12 @@ DO $$ BEGIN
PERFORM pg_terminate_backend(pid, 180000) FROM pg_stat_activity
WHERE application_name = 'fdw_conn_check';
END $$;
-SELECT CASE WHEN closed IS NOT false THEN 1 ELSE 0 END
+SELECT server_name, CASE WHEN closed IS NOT false THEN 'true' ELSE 'false' END AS remote_conn_closed,
+CASE WHEN remote_backend_pid IS NOT NULL THEN 'available' ELSE 'not available' END AS remote_backend_pid
FROM postgres_fdw_get_connections(true);
- case
-------
- 1
+ server_name | remote_conn_closed | remote_backend_pid
+-------------+--------------------+--------------------
+ loopback | true | available
(1 row)
-- Clean up
diff --git a/contrib/postgres_fdw/postgres_fdw--1.1--1.2.sql b/contrib/postgres_fdw/postgres_fdw--1.1--1.2.sql
index 81aad4fcdaa..720401b3c21 100644
--- a/contrib/postgres_fdw/postgres_fdw--1.1--1.2.sql
+++ b/contrib/postgres_fdw/postgres_fdw--1.1--1.2.sql
@@ -12,7 +12,7 @@ DROP FUNCTION postgres_fdw_get_connections ();
CREATE FUNCTION postgres_fdw_get_connections (
IN check_conn boolean DEFAULT false, OUT server_name text,
OUT user_name text, OUT valid boolean, OUT used_in_xact boolean,
- OUT closed boolean)
+ OUT closed boolean, OUT remote_backend_pid INT4)
RETURNS SETOF record
AS 'MODULE_PATHNAME', 'postgres_fdw_get_connections_1_2'
LANGUAGE C STRICT PARALLEL RESTRICTED;
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 1598d9e0862..cee12c0f92e 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -3410,8 +3410,10 @@ DROP SERVER loopback3 CASCADE;
-- List all the existing cached connections. loopback and loopback3
-- should be output as invalid connections. Also the server name and user name
-- for loopback3 should be NULL because both server and user mapping were
--- dropped.
-SELECT server_name, user_name = CURRENT_USER as "user_name = CURRENT_USER", valid, used_in_xact, closed
+-- dropped. remote_backend_pid will continue to return available as it fetch remote
+-- server backend pid from cached connections.
+SELECT server_name, user_name = CURRENT_USER as "user_name = CURRENT_USER", valid, used_in_xact, closed,
+CASE WHEN remote_backend_pid = ANY(SELECT pid FROM pg_stat_activity WHERE backend_type = 'client backend' AND pid <> pg_backend_pid()) then 'available' ELSE 'not available' END AS remote_backend_pid
FROM postgres_fdw_get_connections() ORDER BY 1;
-- The invalid connections get closed in pgfdw_xact_callback during commit.
COMMIT;
@@ -4288,7 +4290,8 @@ SELECT 1 FROM ft1 LIMIT 1;
-- Since the remote server is still connected, "closed" should be FALSE,
-- or NULL if the connection status check is not available.
-SELECT CASE WHEN closed IS NOT true THEN 1 ELSE 0 END
+SELECT server_name, CASE WHEN closed IS NOT true THEN 'false' ELSE 'true' END AS remote_conn_closed,
+CASE WHEN remote_backend_pid = (SELECT pid FROM pg_stat_activity WHERE application_name = 'fdw_conn_check') THEN 'available' ELSE 'not available' END AS remote_backend_pid
FROM postgres_fdw_get_connections(true);
-- After terminating the remote backend, since the connection is closed,
@@ -4298,7 +4301,8 @@ DO $$ BEGIN
PERFORM pg_terminate_backend(pid, 180000) FROM pg_stat_activity
WHERE application_name = 'fdw_conn_check';
END $$;
-SELECT CASE WHEN closed IS NOT false THEN 1 ELSE 0 END
+SELECT server_name, CASE WHEN closed IS NOT false THEN 'true' ELSE 'false' END AS remote_conn_closed,
+CASE WHEN remote_backend_pid IS NOT NULL THEN 'available' ELSE 'not available' END AS remote_backend_pid
FROM postgres_fdw_get_connections(true);
-- Clean up
diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index d2998c13d5d..ff1ec8fb121 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -854,7 +854,7 @@ OPTIONS (ADD password_required 'false');
postgres_fdw_get_connections(
IN check_conn boolean DEFAULT false, OUT server_name text,
OUT user_name text, OUT valid boolean, OUT used_in_xact boolean,
- OUT closed boolean)
+ OUT closed boolean, OUT remote_backend_pid INT4)
returns setof record
@@ -882,11 +882,11 @@ OPTIONS (ADD password_required 'false');
Example usage of the function:
postgres=# SELECT * FROM postgres_fdw_get_connections(true);
- server_name | user_name | valid | used_in_xact | closed
--------------+-----------+-------+--------------+--------
- loopback1 | postgres | t | t | f
- loopback2 | public | t | t | f
- loopback3 | | f | t | f
+ server_name | user_name | valid | used_in_xact | closed | remote_backend_pid
+-------------+-----------+-------+--------------+-----------------------------
+ loopback1 | postgres | t | t | f | 1353340
+ loopback2 | public | t | t | f | 1353120
+ loopback3 | | f | t | f | 1353156
The output columns are described in
.
@@ -951,6 +951,16 @@ postgres=# SELECT * FROM postgres_fdw_get_connections(true);
is not available on this platform.
+
+ remote_backend_pid
+ int4
+
+ Process ID of remote backend handling connection. If valid
+ is set to false (i.e., marked as invalid), this will be
+ process ID of remote backend which handled this connection. NULL
+ is returned if no backend assigned to this connection or connection status is bad.
+
+