Re: Default Stats Revisited

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Robert Treat <xzilla(at)users(dot)sourceforge(dot)net>
Cc: josh(at)agliodbs(dot)com, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "scott(dot)marlowe" <scott(dot)marlowe(at)ihs(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Default Stats Revisited
Date: 2004-03-12 02:29:51
Message-ID: 200403120229.i2C2Tpk11246@candle.pha.pa.us
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Robert Treat wrote:
> On Thursday 11 March 2004 14:17, Josh Berkus wrote:
> > Tom,
> >
> > > Maybe you should ask on -admin or -general. Personally I thought there
> > > wasn't anything to say until someone did some experiments to show
> > > whether an indexed-column differential is really worthwhile and what a
> > > plausible default value would be. The idea sounds good in the abstract,
> > > but will it really help or just be another useless setting?
> >
> > Yeah, that's our next step, a test.
> >
> > On Monday, I hope to have comparative stats for a difficult database on
> > the 3 solutions (leaving things as-is, raising the general default stats,
> > and doing index_stats).
>
> Do you plan on handeling primary key columns differently (since they are
> likely to be unique and indexed) ?

Another idea is whether a foreign key column should get extra
statistics?

> Also how will you handle column that are part of expressional indexes (where
> foo is true for example) ?
>
> Final thought... I'm a DBA and I think the straight number is simpler, though
> could be convinced to go with whichever is higher...

Agreed.

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pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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