From: Hiroshi Inoue <Inoue@tpf.co.jp>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: pgsql-hackers@postgresql.org
Subject: Re: MOVE LAST: why?
Date: Thu, 09 Jan 2003 12:18:48 +0900
Message-ID: <3E1CEA18.18E921A0@tpf.co.jp> (raw)
References: <200301072329.h07NT2X28922@candle.pha.pa.us>
<27934.1041984327@sss.pgh.pa.us>
<3E1B9DCD.75859501@tpf.co.jp>
<501.1041997832@sss.pgh.pa.us>
<3E1BA5E6.9463718F@tpf.co.jp>
<863.1042000401@sss.pgh.pa.us>
<3E1BAFF6.B0114A67@tpf.co.jp>
<1082.1042002375@sss.pgh.pa.us>
<3E1BEFFE.88B57516@tpf.co.jp>
<22435.1042065746@sss.pgh.pa.us>
Tom Lane wrote:
>
> Hiroshi Inoue <Inoue@tpf.co.jp> writes:
> > I'm suspicios if we should implement scrollable cursors
> > with the combination of the current MOVE and FETCH implemen-
> > tation. For example the backwards FETCH operation for group
> > nodes isn't implemented properly yet(maybe).
>
> Yeah, backwards scan is not implemented for quite a large number of plan
> node types :-(. I am not sure that it is practical to fix them all.
> I have been toying with the notion of making cursors on complex plans
> safe for FETCH BACKWARD by sticking a MATERIAL node atop the plan, if
> the top plan node isn't one that can handle backwards scan.
>
> The trouble with this of course is that one of the main things people
> like to use cursors for is huge result sets, and materializing those is
> the last thing you want to do :-(
Honestly I'm not so enthusiastic about scrollable cursors.
Even though PostgreSQL provides an efficient scrollable
cursor, I would use it little unless it could survive
across transactions.
Anyway it's too bad that FETCH LAST means FETCH ALL.
regards,
Hiroshi Inoue
http://w2422.nsk.ne.jp/~inoue/
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Cc: Inoue@tpf.co.jp, tgl@sss.pgh.pa.us, pgman@candle.pha.pa.us, pgsql-hackers@postgresql.org
Subject: Re: MOVE LAST: why?
In-Reply-To: <3E1CEA18.18E921A0@tpf.co.jp>
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