Re: [PERFORM] change sample size for statistics

On Mon, Jun 13, 2011 at 6:33 PM, Willy-Bas Loos <willybas(at)gmail(dot)com> wrote:
> On Fri, Jun 10, 2011 at 9:58 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>>
>> It's not 10%.  We use a fixed sample size, which is configurable on the
>> system, table, or column basis.
>
> It seems that you are referring to "alter column set statistics" and
> "default_statistics_target", which are the number of percentiles in the
> histogram  (and MCV's) .
> I mean the number of records that are scanned by analyze to come to the
> statistics for the planner, especially n_disctict.

In 9.0+ you can do ALTER TABLE .. ALTER COLUMN .. SET (n_distinct = ...);

--
Robert Haas
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