From: Greg Stark <gsstark@mit.edu>
To: Gerardo Herzig <gherzig@fmed.uba.ar>
Cc: pgsql-sql@postgresql.org
Subject: Re: an aggregate to return max() - 1 value?
Date: Thu, 4 Mar 2010 20:53:10 +0000
Message-ID: <407d949e1003041253g1812b85bhe8ce0fbd7b1f7159@mail.gmail.com> (raw)
In-Reply-To: <4B901488.6080502@fmed.uba.ar>
References: <20100304200913.GA24865@apartia.fr>
<4B901488.6080502@fmed.uba.ar>
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)
--
greg
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To: pgsql-sql@postgresql.org
Cc: gsstark@mit.edu, gherzig@fmed.uba.ar
Subject: Re: an aggregate to return max() - 1 value?
In-Reply-To: <407d949e1003041253g1812b85bhe8ce0fbd7b1f7159@mail.gmail.com>
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