pg_locks.relation question

[Daniel Westermann <daniel.westermann@xxxxxxxxxxxxxxxx>]

Hi,

session one:

locks=# begin;
BEGIN
locks=# alter table test add column b text;
ALTER TABLE
locks=#

Session 2 querying pg_locks for the PID from above:

locks=# select locktype,relation::regclass,mode from pg_locks where pid = 2026 and locktype = 'relation';
 locktype | relation |        mode        
----------+----------+---------------------
 relation | test     | AccessExclusiveLock
 relation | 17728    | AccessExclusiveLock
 relation | 17726    | ShareLock
(3 rows)

What are these 17728 and 17726 OIDs? Nothing else is happening except these two sessions.

Thanks in advance

Daniel