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Re: regex cache

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PG Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: regex cache
Date: 2008-06-18 21:54:00
Message-ID: 485983F8.8010500@agliodbs.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane wrote:
> Josh Berkus <josh(at)agliodbs(dot)com> writes:
>>> Having said that, I'm not sure it'd help your problem.  If your query is
>>> using more than 32 regexes concurrently, it likely is using $BIGNUM
>>> regexes concurrently.  How do we fix that?
> 
>> Hmmm.  I think there's a lot of ground between 32 and $BIGNUM.  For example, 
>> where I'm hitting a wall is 300 regexes.  Some quick testing on my opteron 
>> text machine right now shows that the execution time difference between 20rx 
>> and 50rx is around 20x.
> 
> Hmm.  Well, I still don't want to tie it to work_mem; how do you feel
> about a new GUC to determine the max number of cached REs?

Yeah.  You know me, I was just trying to avoid having more GUCs.

--Josh

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