Re: pg_upgrade and statistics

On Tue, Mar 13, 2012 at 01:18:58PM -0500, Kevin Grittner wrote:
> Greg Stark <stark(at)mit(dot)edu> wrote:
> > Daniel Farina <daniel(at)heroku(dot)com> wrote:
> >> You probably are going to ask: "why not just run ANALYZE and be
> >> done with it?"
> >
> > Uhm yes. If analyze takes a long time then something is broken.
> > It's only reading a sample which should be pretty much a fixed
> > number of pages per table. It shouldn't take much longer on your
> > large database than on your smaller databases.
>
> On a small database:
>
> cc=# analyze "CaseHist";
> ANALYZE
> Time: 255.107 ms
> cc=# select relpages, reltuples from pg_class where relname =
> 'CaseHist';
> relpages | reltuples
> ----------+-----------
> 1264 | 94426
> (1 row)
>
> Same table on a much larger database (and much more powerful
> hardware):
>
> cir=# analyze "CaseHist";
> ANALYZE
> Time: 143450.467 ms
> cir=# select relpages, reltuples from pg_class where relname =
> 'CaseHist';
> relpages | reltuples
> ----------+-------------
> 3588659 | 2.12391e+08
> (1 row)
>
> Either way, there are about 500 tables in the database.

That is 2.5 minutes. How large is that database?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +