Re: Incorrect expected rows by ANALYZE

From: pgsql(at)mohawksoft(dot)com
To: tgl(at)sss(dot)pgh(dot)pa(dot)us
Cc: sugita(at)srapc1327(dot)sra(dot)co(dot)jp, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Incorrect expected rows by ANALYZE
Date: 2003-04-07 15:21:27
Message-ID: 1210.68.163.104.172.1049728887.squirrel@mail.mohawksoft.com
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> Kenji Sugita <sugita(at)srapc1327(dot)sra(dot)co(dot)jp> writes:
>> Why do dead tuples cause incorrect expected rows by ANALYZE?
>
> Because it extrapolates the density of live rows in the whole table
> from their density in the first few pages.
>
> There has been some previous discussion of how to improve this, but no
> really workable ideas AFAIR. Ultimately, unless you want to abandon
> the notion that ANALYZE only samples the table and doesn't read the
> whole thing, there will be situations where it gets fooled. But
> possibly we can make those situations less likely to correspond to
> common real-world cases.

Couldn't there be an ANALYZE FULL option?

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