Horton

Re: pgstat_send_connstats() introduces unnecessary timestamp and UDP overhead

Laurenz Albe <laurenz.albe@cybertec.at>

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From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@lists.postgresql.org, Michael Paquier <michael@paquier.xyz>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, magnus@hagander.net, pgsql-hackers@postgresql.org
Date: 2021-09-01T08:56:04Z
Lists: pgsql-hackers 
On Tue, 2021-08-31 at 21:16 -0700, Andres Freund wrote:
> On 2021-09-01 05:39:14 +0200, Laurenz Albe wrote:
> > On Tue, 2021-08-31 at 18:55 -0700, Andres Freund wrote:
> > > > > On Tue, Aug 31, 2021 at 04:55:35AM +0200, Laurenz Albe wrote:In the
> > > > > view of that, how about doubling PGSTAT_STAT_INTERVAL to 1000
> > > > > milliseconds?  That would mean slightly less up-to-date statistics, but
> > > > > I doubt that that will be a problem.
> > > 
> > > I think it's not helpful. Still increases the number of messages substantially in workloads
> > > with a lot of connections doing occasional queries. Which is common.
> > 
> > How come?  If originally you send table statistics every 500ms, and now you send
> > table statistics and session statistics every second, that should amount to the
> > same thing.  Where is my misunderstanding?
> 
> Consider the case of one query a second.

I guess I am too stupid.  I don't see it.

Yours,
Laurenz Albe

Commits

  1. Fix performance regression from session statistics.

  2. Add pg_stat_database counters for sessions and session time