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Re: Use of index in 7.0 vs 6.5

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: "Mikheev, Vadim" <vmikheev(at)SECTORBASE(dot)COM>, "'Hiroshi Inoue'" <Inoue(at)tpf(dot)co(dot)jp>, 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: 2000-05-25 16:08:45
Message-ID: 200005251608.MAA25042@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-sql
> 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


-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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