From: | Glyn Astill <glynastill(at)yahoo(dot)co(dot)uk> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Trigger function cost |
Date: | 2009-04-09 16:45:23 |
Message-ID: | 726087.12777.qm@web23605.mail.ird.yahoo.com |
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Thread: | |
Lists: | pgsql-general |
> From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
>
> > Is there any reason to mess with this?
>
> No. The planner doesn't actually bother to figure the
> cost of triggers
> anyway, since presumably every correct plan will fire the
> same set of
> triggers. So even if you had a more accurate cost estimate
> than that
> one, it wouldn't get used for anything.
>
Excellent, that's good with me.
> Now, for ordinary non-trigger functions, it might be worth
> paying
> some attention to the cost estimate. "1" is
> intended to denote the
> cost of a reasonably simple C function, so PL functions
> should pretty
> much always have costs that are large multiples of that.
> 100 is a
> reasonable default, but if you know better you can put
> something else.
>
Cool, I'll leave it alone for now then, interesting stuff, thanks Tom.
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