Re: == PostgreSQL Weekly News - February 21 2010 ==

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От David Fetter
Тема Re: == PostgreSQL Weekly News - February 21 2010 ==
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Msg-id 20100222154007.GK2917@fetter.org
обсуждение исходный текст
Ответ на == PostgreSQL Weekly News - February 21 2010 ==  (David Fetter <david@fetter.org>)
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On Sun, Feb 21, 2010 at 11:55:34PM -0800, David Fetter wrote:
> == PostgreSQL 9.0 Feature of the Week ==
>
> You can now control the behavior of distinct values per column using
> ALTER TABLE...ALTER COLUMN...SET STATISTICS DISTINCT.  Positive
> numbers are assumed to be the number of distinct values, 0 tells the
> planner to use the results from ANALYZE, and negative numbers (which
> should be between -1 and 0, cause the planner to estimate the number
> of distinct values as the estimated number of rows multiplied by the
> absolute value of the number.

This has changed since it was originally written.  The syntax now is

    ALTER TABLE..ALTER COLUMN...SET (attribute=value, ...)

For 9.0, attribute can be n_distinct or n_distinct_inherited, and this
may expand in future major versions.

Thanks to Robert Haas for pointing this out :)

Cheers,
David.
--
David Fetter <david@fetter.org> http://fetter.org/
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