From: Tom Lane <tgl@sss.pgh.pa.us>
To: Teodor Sigaev <teodor@sigaev.ru>
Cc: Pgsql Hackers <pgsql-hackers@postgresql.org>
Subject: Re: [PATCHES] GIN improvements
Date: Thu, 24 Jul 2008 16:30:09 -0400
Message-ID: <10899.1216931409@sss.pgh.pa.us> (raw)
In-Reply-To: <4888D6DB.8030100@sigaev.ru>
References: <483FD205.4090904@sigaev.ru>
<486BC501.6060605@sigaev.ru>
<27880.1215810535@sss.pgh.pa.us>
<487A6E0C.3090600@sigaev.ru>
<8993.1216843701@sss.pgh.pa.us>
<4888A594.6010102@sigaev.ru>
<7913.1216918895@sss.pgh.pa.us>
<4888D6DB.8030100@sigaev.ru>
Teodor Sigaev <teodor@sigaev.ru> writes:
> - GiST already supports both scan directions in theory, but page split may
> change order between forward and backward scans (user-defined pageSplit doesn't
> preserve order of tuples). Holding of split until end of scan will produce
> unacceptable concurrency level.
> - GIN doesn't support backward scan direction and will not support in close
> future.
Okay. I'll see about fixing the planner to not assume that GIST or GIN
indexscans are scrollable.
The cleanest way to do this is to introduce a new bool column in pg_am
rather than hard-wiring assumptions about which AMs can do it. However
(a) that's not back-patchable and (b) it'll create a merge conflict with
your patch, if you're still going to add a new AM function column.
I think that aminsertcleanup per se isn't needed, but if we want an
"amanalyze" there'd still be a conflict. Where are we on that?
regards, tom lane
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To: pgsql-patches@postgresql.org
Cc: tgl@sss.pgh.pa.us, teodor@sigaev.ru, pgsql-hackers@postgresql.org
Subject: Re: [PATCHES] GIN improvements
In-Reply-To: <10899.1216931409@sss.pgh.pa.us>
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