From: PFC <lists@peufeu.com>
To: Jim C. Nasby <jnasby@pervasive.com>
Cc: pgsql-performance@postgresql.org
Cc: pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] Big IN() clauses etc : feature proposal
Date: Wed, 10 May 2006 21:35:39 +0200
Message-ID: <op.s9coppqfcigqcu@apollo13> (raw)
In-Reply-To: <20060510192401.GQ99570@pervasive.com>
References: <445F7FF8.6070707@comcast.net>
<1147110142.32369.7.camel@archimedes>
<20060508175013.GY99570@pervasive.com>
<28288.1147111196@sss.pgh.pa.us>
<op.s89zl30wcigqcu@apollo13>
<8764kfz1iq.fsf@stark.xeocode.com>
<op.s9alfhjrcigqcu@apollo13>
<20060510192401.GQ99570@pervasive.com>
> On Tue, May 09, 2006 at 06:29:31PM +0200, PFC wrote:
>> You mean the cursors'storage is in fact the same internal machinery
>> as a temporary table ?
>
> Use the source, Luke...
LOL, yeah, I should have, sorry.
> See tuplestore_begin_heap in backend/utils/sort/tuplestore.c and
> heap_create_with_catalog in backend/catalog/heap.c. You'll find that
> creating a tuplestore is far easier than creating a temp table.
I had used intuition (instead of the source) to come at the same
conclusion regarding the level of complexity of these two...
But I'll look at the source ;)
> Perhaps it would be worth creating a class of temporary tables that used
> a tuplestore, although that would greatly limit what could be done with
> that temp table.
Just selecting from it I guess, but that's all that's needed. Anymore
would duplicate the functionality of a temp table.
I find cursors awkward. The application can FETCH from them, but postgres
itself can't do it in SQL, unless using FOR.. IN in plpgsql...
It would be a powerful addition to be able to split queries, factor out
common parts between multiple queries, etc, using this system, it can even
be used to execute an inner part of a query, then plan the rest according
to the results and execute it... without the overhead of a temp table.
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To: pgsql-performance@postgresql.org
Cc: lists@peufeu.com, jnasby@pervasive.com, pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] Big IN() clauses etc : feature proposal
In-Reply-To: <op.s9coppqfcigqcu@apollo13>
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