Message-ID: <450875FC.9040907@logix-tt.com>
Date: Wed, 13 Sep 2006 23:19:56 +0200
From: Markus Schaber <schabi@logix-tt.com>
Organization: Logical Tracking and Tracing International AG, Switzerland
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To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: PostgreSQL SQL List <pgsql-sql@postgresql.org>
Subject: Re: Aggregates with internal state type?
References: <45086B40.3000200@logix-tt.com> <16722.1158181987@sss.pgh.pa.us>
In-Reply-To: <16722.1158181987@sss.pgh.pa.us>
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Hi, Tom,

Tom Lane wrote:
> Markus Schaber <schabi@logix-tt.com> writes:
>> This lead me to the question whether it is possible to use "internal" as
>> state type for an Aggregate whose functions are implemented in C.
> 
> No, because the system has no idea what the representation of an
> "internal" state value might be, and in particular how to copy it.
> The same goes for other pseudotypes.

Ah, I see. So there's no possibility to pass some void* kind of
intermediate data, I have to craft at least a dummy PostgreSQL datatype
for it.

This also solves the question how such things would be cleaned up in
case of an intermediate error.

Thanks,

Markus

-- 
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org