Re: avoid select expens_expr(col) like unneccessary calculations

From: Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>
To: Markus Bertheau <twanger(at)bluetwanger(dot)de>
Cc: <pgsql-sql(at)postgresql(dot)org>
Subject: Re: avoid select expens_expr(col) like unneccessary calculations
Date: 2003-07-07 22:47:06
Message-ID: 20030707154329.J82767-100000@megazone23.bigpanda.com
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On 8 Jul 2003, Markus Bertheau wrote:

> when you have
> select expensive_expression(column), * from table offset 20 limit 40
>
> can you somehow save the cost for the first 20 calculations of
> expensive_expression?

Right now the only way I can think of that might work is to push the
offset/limit into a subselect on table and then do the
expensive_expression at the top level.

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