Re: proposal for 9.5: monitoring lock time for slow queries

From: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: proposal for 9.5: monitoring lock time for slow queries
Date: 2014-08-13 04:18:43
Message-ID: CAB7nPqSP97fU9Tom=+UYWpXrNBTrAG2ggRwazDJvsnC9dtBZcw@mail.gmail.com
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On Wed, Aug 13, 2014 at 4:59 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> Any idea how to show a lock time in some practical form together with logged
> slow query?

Doing a join on pg_stat_activity and pg_locks is not going to help
much as you could only get the moment when query has started or its
state has changed. Have you thought about the addition of a new column
in pg_locks containing the timestamp of the moment a lock has been
taken? I am sure that we are concerned about the performance impact
that extra calls to gettimeofday could have though...
Regards,
--
Michael

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