Re: pg_locks.relation question

On Wed, Apr 18, 2018 at 5:35 PM, Daniel Westermann < [ mailto:daniel(dot)westermann(at)dbi-services(dot)com | daniel(dot)westermann(at)dbi-services(dot)com ] > wrote:

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.

>>Those are probably the OIDs of the toast table and the index on it. If you commit the transaction running in Session 1 and then query >>pg_class for those OIDs, you might see more details. Of course, I am just guessing without looking into much detail.

Thx, Pavan, that's it.