From: | "Dobes Vandermeer" <dobesv(at)gmail(dot)com> |
---|---|
To: | "Sean Davis" <sdavis2(at)mail(dot)nih(dot)gov> |
Cc: | pgsql-novice(at)postgresql(dot)org |
Subject: | Re: Optimizing sum() operations |
Date: | 2008-10-03 19:13:59 |
Message-ID: | 7324d9a20810031213s53082483h72248315df794272@mail.gmail.com |
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Lists: | pgsql-novice |
On Fri, Oct 3, 2008 at 4:51 AM, Sean Davis <sdavis2(at)mail(dot)nih(dot)gov> wrote:
> On Fri, Oct 3, 2008 at 4:51 AM, Dobes Vandermeer <dobesv(at)gmail(dot)com> wrote:
>> I'm currently using sum() to compute historical values in reports;
>> basically select sum(amount) on records where date <= '...' and date
>>>= '...' who = X.
>>
>> Second, if this is a concern, is there a best practice for optimizing
>> these kinds of queries?
>
> You'll need to test to see what performance you get. That said,
> indexing is a good place to start. You can always run explain and
> explain analyze on the queries to double-check the planner.
Could I create an index that includes a sum() function - like:
create index sumidx on records (who, date, sum(amount)) ?
I'm sure that theoretically this is possible, but does postgres support it?
--
Dobes Vandermeer
Director, Habitsoft Inc.
dobesv(at)habitsoft(dot)com
778-891-2922
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