Re: Update blocking a select count(*)? - Mailing list pgsql-performance

Peter Geoghegan <peter@2ndquadrant.com> wrote:
> Benedict Holland <benedict.m.holland@gmail.com> wrote:
>> Do I seem to have this right and is there anything I can do?
>
> There are a couple of maintenance operations that could block a
> select. Do you see any AccessExclusive locks within pg_locks?
> That's the only type of lock that will block a select statement's
> AccessShare lock.

To check for that, see the queries on these Wiki pages:

http://wiki.postgresql.org/wiki/Lock_Monitoring
http://wiki.postgresql.org/wiki/Lock_dependency_information

-Kevin