From: Teodor Sigaev <teodor@sigaev.ru>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Oleg Bartunov <oleg@sai.msu.su>
Cc: Pgsql Hackers <pgsql-hackers@postgresql.org>
Subject: Re: [PATCHES] GIN improvements
Date: Tue, 22 Jul 2008 22:24:40 +0400
Message-ID: <488625E8.4070203@sigaev.ru> (raw)
In-Reply-To: <1636.1216749010@sss.pgh.pa.us>
References: <483FD205.4090904@sigaev.ru>
<486BC501.6060605@sigaev.ru>
<27880.1215810535@sss.pgh.pa.us>
<487A6E0C.3090600@sigaev.ru>
<29437.1216742605@sss.pgh.pa.us>
<48861758.4070507@sigaev.ru>
<1636.1216749010@sss.pgh.pa.us>
> Well, if that is required to be true then this whole design is pretty
> broken, because VACUUM doesn't hold any lock that would guarantee that
> no insert happens between the two calls. If we fold the two AM calls
> into one call then it'd be okay for the index AM to take such a lock
> transiently during the single index-cleanup-plus-bulkdelete call.
Actually, lock doesn't needed. Just bulkdelete should not try to remove not yet
"insertcleanuped" items pointer. That's easy because VacPageList is prepared
before insertcleanup call.
> Maybe it'd be better if ambulkdelete *did* scan the pending list?
I don't like that idea because it requires to add a lot of code (concurrent
deletion of pages in list), much simpler to call insertcleanup inside
ginbulkdelete/ginvacuumcleanup.
> You'd still need at least page-level locking but perhaps not anything
> stronger.
That's close to trivial to revert this piece to add cleanup call to
ginbulkdelete/ginvacuumcleanup. Early variants used this variant.
Reasons for new variant was:
- defining needing of call of insertcleanup, and stats argument was used for
it in both function. If it's a NULL then call cleanup.
- I thought about statistic-based trigger for separate call of insertcleanup.
Trigger should be fired on massive insert/update events very similar to
trigger on massive delete for ambulkdelete. I'm very sorry but I didn't do it
yet, and definitely I need some help here.
Do I revert that piece?
--
Teodor Sigaev E-mail: teodor@sigaev.ru
WWW: http://www.sigaev.ru/
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To: pgsql-patches@postgresql.org
Cc: teodor@sigaev.ru, tgl@sss.pgh.pa.us, oleg@sai.msu.su, pgsql-hackers@postgresql.org
Subject: Re: [PATCHES] GIN improvements
In-Reply-To: <488625E8.4070203@sigaev.ru>
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