Re: User Defined Functions/AM's inherently slow?

From: Eric Ridge <ebr(at)tcdi(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: User Defined Functions/AM's inherently slow?
Date: 2004-01-18 04:46:32
Message-ID: 49E784E9-4971-11D8-B3E7-000A95BB5944@tcdi.com
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On Jan 17, 2004, at 11:33 PM, Tom Lane wrote:
> The difference between "total runtime" and the top plan node's runtime
> has to represent plan startup/shutdown time. I'm suspicious that your
> stubs are somehow not initializing something, though on first glance I
> do not see what.

I can't see anything either... which is why I brought it up. I'm still
a noob with this stuff, and thought maybe I was just missing something.

> Theory B would be that there's some huge overhead in calling
> non-built-in
> functions on your platform. We do know that looking up a "C" function
> is
> significantly more expensive than looking up a "builtin" function, but
> there should only be half a dozen such calls involved in this test
> case;
> it's hard to credit that that takes 200 msec. Does the time drop at
> all
> on second and subsequent repetitions in a single backend run?

Yes, it drops from about .680ms to the .250ish that I posted.

I suppose I should try compiling this little stub into postgres, eh?

eric

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