Re: Use of index in 7.0 vs 6.5 - Mailing list pgsql-sql

From Bruce Momjian
Subject Re: Use of index in 7.0 vs 6.5
Date
Msg-id 200005251608.MAA25042@candle.pha.pa.us
Whole thread Raw
In response to Re: Use of index in 7.0 vs 6.5  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses RE: Use of index in 7.0 vs 6.5  ("Hiroshi Inoue" <Inoue@tpf.co.jp>)
List pgsql-sql
> Bruce Momjian <pgman@candle.pha.pa.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@candle.pha.pa.us               |  (610)
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