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Re: Implementation of aggregate functions

From: Neil Conway <neilc(at)samurai(dot)com>
To: sayali k <sayali_s_kulkarni(at)yahoo(dot)co(dot)in>
Cc: pgsql-patches(at)postgresql(dot)org
Subject: Re: Implementation of aggregate functions
Date: 2007-09-20 06:52:10
Message-ID: 1190271130.3210.2.camel@goldbach (view raw or flat)
Thread:
Lists: pgsql-patches
The pgsql-patches mailing list is for submitting modifications to
Postgres, not for asking these sorts of questions.

On Thu, 2007-20-09 at 06:49 +0100, sayali k wrote:
> I am keen in implementing certain additional aggregate
> functions like percentage, standard deviation etc. I
> would like to know the complexity of this and also the
> parts of the code which would have to be modified for
> the same,

stddev() already exists. Take a look at the implementation of the
existing aggregate functions, which can be found in
src/backend/utils/adt (float.c, numeric.c, etc.) There is no need to
modify the core Postgres backend code to add new aggregate functions, of
course.

I suggest doing a modicum of research first, and then asking on
pgsql-hackers if you have more specific questions about Postgres
internals.

-Neil



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