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List:       postgresql-admin
Subject:    Re: [ADMIN] determining which operation is blocking another query
From:       Michael Fuhr <mike () fuhr ! org>
Date:       2006-05-25 7:27:07
Message-ID: 20060525072707.GA31892 () winnie ! fuhr ! org
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On Wed, May 24, 2006 at 11:49:37PM -0700, Sriram Dandapani wrote:
> Is there a system view that can be used to determine which
> INSERT/UPDATE/DELETE/Other Operation is blocking a SELECT statement.

Query pg_locks to see what locks transactions have acquired or are
waiting to acquire.  If you have stats_command_string enabled then
querying pg_stat_activity should show sessions' current queries.

Are you sure SELECT is blocked, or could it just be taking a long
time?  MVCC allows SELECT to run concurrently with INSERT, UPDATE,
and DELETE without blocking; only a few operations like VACUUM FULL
block an ordinary SELECT (without FOR SHARE or FOR UPDATE).

-- 
Michael Fuhr

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