Re: [PERFORM] change sample size for statistics

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.

On Fri, Jun 10, 2011 at 10:06 PM, Nathan Boley <npboley(at)gmail(dot)com> wrote:

> If you need to fix ndistinct, a better approach may be to do it manually.
>

That would be nice, but how do i prevent the analyzer to overwrite
n_distinct without blocking the generation of new histogram values etc for
that column?

We use version 8.4 at the moment (on debian squeeze).

Cheers,

WBL
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