Postgres Pro
Downloads
Home   >   mailing lists

Re: concurrent SELECT blocking ALTER? - Mailing list pgsql-general

From Neil Harkins
Subject Re: concurrent SELECT blocking ALTER?
Date
Msg-id CAMtfGdXTv4UvcYNzsxW8M1j9jLOj-Yg6u-m8rz7vPOpDZDZq2Q@mail.gmail.com
Whole thread Raw
In response to Re: concurrent SELECT blocking ALTER?  (Thomas Kellerer <spam_eater@gmx.net>)
Responses Re: concurrent SELECT blocking ALTER?  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-general
Tree view
Note the number of exclusive locks in my first message, it is equal to the number of threads (20). Also, the ALTER was not running then, apologies if that was not clear.

On Wednesday, January 29, 2014, Thomas Kellerer <spam_eater@gmx.net> wrote:
Neil Harkins wrote on 29.01.2014 23:37:
I totally understand DDL taking exclusive locks, the problem here seems to be that the *SELECTs*
are taking out exclusive locks, locking out the ALTER, which feels like a bug.

The SELECT is not holding an exclusive lock, it's holing a *shared* lock, but the ALTER is _requesting_ an exclusive lock and that can only be granted until all shared (or otherwise incompatible) locks are released.





--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

pgsql-general by date:

Previous
From: Thomas Kellerer
Date:
Subject: Re: concurrent SELECT blocking ALTER?
Next
From: Jeff Janes
Date:
Subject: Re: concurrent SELECT blocking ALTER?