| From: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Hannu Krosing <hannu(at)skype(dot)net>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: \d on database with a lot of tables is slow |
| Date: | 2005-10-04 14:17:33 |
| Message-ID: | 20051004141733.GF40138@pervasive.com |
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| Lists: | pgsql-hackers |
On Sat, Oct 01, 2005 at 02:00:12PM -0400, Tom Lane wrote:
> I wrote:
> > It's presumably mostly in the pg_table_is_visible() calls.
>
> I did some profiling on a test case with 10000 tables, and noticed that
> a big part of the problem is that the catalog caches become entirely
> useless: almost every catcache lookup ends up going to the underlying
> tables. This is because MAXCCTUPLES in catcache.c is fixed at 5000,
> and that's not an adequate working set for this many tables. If you
> are willing to throw memory at the problem, you could try increasing
> MAXCCTUPLES (to say 50K or 100K) and see if that helps.
Out of curiosity... does catcache cache all pg_* tables? Also, at what
point would it be good to up NCCBUCKETS?
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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