On Mon, Jun 13, 2011 at 6:33 PM, Willy-Bas Loos <willybas@gmail.com> wrote:
> On Fri, Jun 10, 2011 at 9:58 PM, Josh Berkus <josh@agliodbs.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
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company