From: Jim C. Nasby <jim@nasby.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Erik Jones <erik@myemma.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: More 8.2 client issues (Was: [Slow dump?)
Date: Wed, 10 Jan 2007 14:07:54 -0600
Message-ID: <20070110200753.GR12217@nasby.net> (raw)
In-Reply-To: <12515.1167843380@sss.pgh.pa.us>
References: <459AD5A8.7030102@myemma.com>
<22512.1167779361@sss.pgh.pa.us>
<459BD61C.3030202@myemma.com>
<11617.1167841479@sss.pgh.pa.us>
<459BDC98.8030008@myemma.com>
<12515.1167843380@sss.pgh.pa.us>
On Wed, Jan 03, 2007 at 11:56:20AM -0500, Tom Lane wrote:
> Erik Jones <erik@myemma.com> writes:
> > Tom Lane wrote:
> >> I could see this taking an unreasonable amount of time if you had a huge
> >> number of pg_class rows or a very long search_path --- is your database
> >> at all out of the ordinary in those ways?
> >>
> > Well, running "select count(*) from pg_class;" returns 524699 rows
>
> Ouch.
>
> > our search path is the default. I'd also like to reiterate that \d
> > pg_class returns instantly when run from the 8.1.4 psql client connected
> > to the 8.2 db.
>
> I think I know where the problem is: would you compare timing of
>
> select * from pg_class where c.relname ~ '^(pg_class)$';
>
> select * from pg_class where c.relname ~ '^pg_class$';
>
> Recent versions of psql put parentheses into the regex pattern for
> safety in case it's got "|", but I just realized that that probably
> confuses the optimizer's check for an indexable regex :-(
>
> However, this only explains slowdown in psql's \d commands, which
> wasn't your original complaint ...
On the other hand, with 500k relations pg_dump is presumably going to be
doing a lot of querying of the catalog tables, so if it uses similar
queries...
--
Jim Nasby jim@nasby.net
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
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To: pgsql-performance@postgresql.org
Cc: jim@nasby.net, tgl@sss.pgh.pa.us, erik@myemma.com
Subject: Re: More 8.2 client issues (Was: [Slow dump?)
In-Reply-To: <20070110200753.GR12217@nasby.net>
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