From: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
---|---|
To: | Stephen Frost <sfrost(at)snowman(dot)net> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: constraint exclusion analysis caching |
Date: | 2008-05-09 20:25:34 |
Message-ID: | 4824B33E.8080705@dunslane.net |
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Lists: | pgsql-hackers |
Stephen Frost wrote:
> * Gregory Stark (stark(at)enterprisedb(dot)com) wrote:
>
>> "Andrew Dunstan" <andrew(at)dunslane(dot)net> writes:
>>
>>
>>> Actual execution of the query in question was talking one tenth of that
>>> time.
>>> ...
>>> but in principle it seems silly to keep paying the same penalty over and
>>> over again.
>>>
>> I would think constraint_exclusion only really makes sense if you're spending
>> a lot more time executing than planning queries. Either that means you're
>> preparing queries once and then executing them many many times or you're
>> planning much slower queries where planning time is insignificant compared to
>> the time to execute them.
>>
>
> Would it be possible to change the application to use prepared queries?
> Seems like that'd make more sense the changing it to use the child
> tables directly.. Just my 2c.
>
>
>
This is actually a technique already used elsewhere in the app, so it
will fit quite well. Thanks for the suggestion, though.
(BTW, why does your MUA set Mail-Followup-To: (and do it badly, what's
more) ?)
cheers
andrew
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