From: Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
To: pgsql-sql@postgresql.org
Subject: Re: an aggregate to return max() - 1 value?
Date: Sat, 6 Mar 2010 14:31:27 +0100
Message-ID: <20100306133127.GA6562@apartia.fr> (raw)
In-Reply-To: <407d949e1003041253g1812b85bhe8ce0fbd7b1f7159@mail.gmail.com>
References: <20100304200913.GA24865@apartia.fr>
<4B901488.6080502@fmed.uba.ar>
<407d949e1003041253g1812b85bhe8ce0fbd7b1f7159@mail.gmail.com>
On Thu, Mar 04, 2010 at 08:53:10PM +0000, Greg Stark wrote:
> SELECT col FROM tab ORDER BY col DESC OFFSET 1 LIMIT 1
>
> In 8.4 OLAP window functions provide more standard and flexibility
> method but in this case it wouldn't perform as well:
>
> postgres=# select i from (select i, rank() over (order by i desc) as r
> from i) as x where r = 2;
> i
> ----
> 99
> (1 row)
>
> postgres=# select i from (select i, dense_rank() over (order by i
> desc) as r from i) as x where r = 2;
> i
> ----
> 99
> (1 row)
Wow, I didn't know about window functions until now. It's exactly what I
need.
Thanks Greg, and also thanks to others who sent their suggestion.
Cheers,
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Subject: Re: an aggregate to return max() - 1 value?
In-Reply-To: <20100306133127.GA6562@apartia.fr>
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