Message-ID: <459BE377.1030706@myemma.com>
Date: Wed, 03 Jan 2007 11:10:15 -0600
From: Erik Jones <erik@myemma.com>
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To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: More 8.2 client issues (Was: [Slow dump?)
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>
In-Reply-To: <12515.1167843380@sss.pgh.pa.us>
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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)$';
>   
Approximately 4 seconds.
> 	select * from pg_class where c.relname ~ '^pg_class$';
>   
Instant.
> 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 ...
>   
Well, it explains the slowdown wrt a query against the catalog tables by 
a postgres client application.  Were there any changes made like this to 
pg_dump and/or pg_restore?

-- 
erik jones <erik@myemma.com>
software development
emma(r)