Re: Incorrect expected rows by ANALYZE - Mailing list pgsql-hackers

From pgsql@mohawksoft.com
Subject Re: Incorrect expected rows by ANALYZE
Date
Msg-id 1210.68.163.104.172.1049728887.squirrel@mail.mohawksoft.com
Whole thread Raw
In response to Re: Incorrect expected rows by ANALYZE  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Incorrect expected rows by ANALYZE  ("scott.marlowe" <scott.marlowe@ihs.com>)
List pgsql-hackers
> Kenji Sugita <sugita@srapc1327.sra.co.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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