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Re: Access statistics

From: Jan Wieck <JanWieck(at)Yahoo(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Jan Wieck <JanWieck(at)Yahoo(dot)com>, PostgreSQL HACKERS <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Access statistics
Date: 2001-06-01 14:34:36
Message-ID: 200106011434.f51EYas01443@jupiter.us.greatbridge.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane wrote:
> Jan Wieck <JanWieck(at)Yahoo(dot)com> writes:
> >     So outing myself not beeing a *real programmer*, this is what
> >     I have so far:
>
> Hmm ... what is the performance of all this like?  Seems like a lot
> of overhead.  Can it be turned off?

    Current  performance loss is about 2-4% wallclock measured. I
    expect it to become better when turning some of the functions
    into macros.

    The  plan is to add another column to pg_database that can be
    used to turn it on/off on a per database level. Backends just
    decide  at startup if they collect and send for their session
    lifetime.

> >     * Backends call some collector functions  at  various  places
> >       now  (these  will  finally  be macros), that count up table
> >       scans, tuples returned by scans,  buffer  fetches/hits  and
> >       the like.
>
> Have you removed the existing stats-gathering support
> (backend/access/heap/stats.c and so on)?   That would buy back
> at least a few of the cycles involved ...

    Not sure if we really should.  Let's  later  decide  if  it's
    really obsolete.

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#================================================== JanWieck(at)Yahoo(dot)com #



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