| From: | Josh Berkus <josh(at)agliodbs(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: RFC: replace pg_stat_activity.waiting with something more descriptive |
| Date: | 2015-08-05 00:46:41 |
| Message-ID: | 55C15CF1.4080606@agliodbs.com |
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| Thread: | |
| Lists: | pgsql-hackers |
On 06/25/2015 07:50 AM, Tom Lane wrote:
> To do that, we'd have to change the semantics of the 'waiting' column so
> that it becomes true for non-heavyweight-lock waits. I'm not sure whether
> that's a good idea or not; I'm afraid there may be client-side code that
> expects 'waiting' to indicate that there's a corresponding row in
> pg_locks. If we're willing to do that, then I'd be okay with
> allowing wait_status to be defined as "last thing waited for"; but the
> two points aren't separable.
Speaking as someone who writes a lot of monitoring and alerting code,
changing the meaning of the waiting column is OK as long as there's
still a boolean column named "waiting" and it means "query blocked" in
some way.
Users are used to pg_stat_activity.waiting failing to join against
pg_locks ... for one thing, there's timing issues there. So pretty much
everything I've seen uses outer joins anyway.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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