Skip site navigation (1) Skip section navigation (2)

RE: Use of index in 7.0 vs 6.5

From: "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp>
To: "Bruce Momjian" <pgman(at)candle(dot)pha(dot)pa(dot)us>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Mikheev, Vadim" <vmikheev(at)SECTORBASE(dot)COM>, "Ryan Bradetich" <ryan_bradetich(at)hp(dot)com>, <pgsql-sql(at)postgresql(dot)org>
Subject: RE: Use of index in 7.0 vs 6.5
Date: 2000-05-26 00:02:50
Message-ID: 000301bfc6a5$bb1ce600$2801007e@tpf.co.jp (view raw or flat)
Thread:
Lists: pgsql-sql
> -----Original Message-----
> From: Bruce Momjian [mailto:pgman(at)candle(dot)pha(dot)pa(dot)us]
> 
> > Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > > That certainly would make sense.  We have hesitated to gather more
> > > statistics because of the time involved.  Fuller statistics 
> on just the
> > > indexed columns could be a big win and be done fairly quickly because
> > > the rows are already sorted in the index.
> > 
> > Yeah, a scan over just the index itself would be a perfect way to
> > gather stats.  The normal objection to it (can't tell whether entries
> > correspond to currently-valid tuples) doesn't apply, because we don't
> > really care whether the stats are perfectly accurate.
> > 
> > Should put this in TODO, along with something about splitting the
> > ANALYZE function out of VACUUM and making it invokable as a separate
> > statement.
> 
> Added:
> 
> * Remove ANALYZE from VACUUM so it can be run separately without locks
> * Gather more accurate statistics using indexes
>

Gathering statistics using indexes on-fly is best.
However VACUUM(without ANALYZE) already scans all indexes using
vc_scanoneind()/vc_vaconeind().  Isn't it availble anyway ?

Regards.

Hiroshi Inoue
Inoue(at)tpf(dot)co(dot)jp

In response to

pgsql-sql by date

Next:From: Tom LaneDate: 2000-05-26 00:03:18
Subject: Re: Use of index in 7.0 vs 6.5
Previous:From: Ryan BradetichDate: 2000-05-25 23:40:35
Subject: Re: Use of index in 7.0 vs 6.5

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group