Re: Speeding up Aggregates - Mailing list pgsql-performance

From Bruno Wolff III
Subject Re: Speeding up Aggregates
Date
Msg-id 20031010013522.GB18596@wolff.to
Whole thread Raw
In response to Re: Speeding up Aggregates  (Dror Matalon <dror@zapatec.com>)
Responses Re: Speeding up Aggregates  (Dror Matalon <dror@zapatec.com>)
List pgsql-performance
On Thu, Oct 09, 2003 at 17:44:46 -0700,
  Dror Matalon <dror@zapatec.com> wrote:
>
> How is doing order by limit 1 faster than doing max()? Seems like the
> optimizer will need to sort or scan the data set either way. That part
> didn't actually make a difference in my specific case.

max() will never be evaluated by using an index to find the greatest value.
So in many cases using order by and limit 1 is faster.

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