Re: [COMMITTERS] pgsql-server/ oc/src/sgml/runtime.sgml rc/back

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [COMMITTERS] pgsql-server/ oc/src/sgml/runtime.sgml rc/back
Date: 2002-11-21 03:33:55
Message-ID: 200211210333.gAL3Xt116817@candle.pha.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-committers pgsql-hackers

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Tom, do we really want to add a GUC that is used just for comparison of
> > performance? I know we have the seqscan on/off, but there are valid
> > reasons to do that. Do you think there will be cases where it will
> > faster to have this hash setting off?
>
> Sure --- that's why the planner code is going to great lengths to try to
> choose the faster one. Even if I didn't think that, it'll be at least
> as useful as, say, enable_indexscan.

Oh, OK. Just checking. I was confused about your commit message
because you seemed to be saying it was mostly for testing, and I thought
you meant testing to see if the hash code is an improvement over what we
had, rather than to see if the hash code is an improvement over the
sequential scan GROUP BY path, which is still in the code.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073

In response to

Browse pgsql-committers by date

  From Date Subject
Next Message Tom Lane 2002-11-21 03:37:33 Re: pgsql-server/ oc/src/sgml/runtime.sgml rc/back ...
Previous Message Tom Lane 2002-11-21 03:30:20 Re: [COMMITTERS] pgsql-server/ oc/src/sgml/runtime.sgml rc/back ...

Browse pgsql-hackers by date

  From Date Subject
Next Message Tom Lane 2002-11-21 03:37:33 Re: pgsql-server/ oc/src/sgml/runtime.sgml rc/back ...
Previous Message Tom Lane 2002-11-21 03:30:20 Re: [COMMITTERS] pgsql-server/ oc/src/sgml/runtime.sgml rc/back ...