Hi All, 

 I'm trying to gain a good understanding of how PostgreSQL determines
what to sample when doing a stats analysis on a table. Using PostgreSQL
7.4's pg_stats table I can get a good overall understanding of
variations in the table, but I need to know how PostgreSQL makes it's
choices on what rows to sample. The other thing I also noted, is that I
can change the stats of a column to be as high as 1000, but PostgreSQL
still may not sample all 1000 elements..

 can someone help me gain a good understanding of that area of Postgres
so that I can make better choices on optimizing?

-- 
Chris Bowlby <chris@pgsql.com>
PostgreSQL Inc.


Mon, 29 Mar 2004 11:07:44 -0400
Chris Bowlby <chris@pgsql.com>
Row sampling..
Chris Bowlby <chris@pgsql.com> writes:
> I need to know how PostgreSQL makes it's
> choices on what rows to sample.

Randomly.

			regards, tom lane

Mon, 29 Mar 2004 10:46:13 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: Row sampling.. 