From: | Andrey Borodin <x4mmm(at)yandex-team(dot)ru> |
---|---|
To: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
Cc: | Peter Geoghegan <pg(at)bowt(dot)ie>, Andres Freund <andres(at)anarazel(dot)de>, chenhj <chjischj(at)163(dot)com>, Teodor Sigaev <teodor(at)sigaev(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Connections hang indefinitely while taking a gin index's LWLock buffer_content lock |
Date: | 2018-12-12 13:08:04 |
Message-ID: | 1C6E203B-71D9-46D1-AB8F-19A75323C2BE@yandex-team.ru |
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Lists: | pgsql-hackers |
Hi!
> 12 дек. 2018 г., в 3:26, Alexander Korotkov <aekorotkov(at)gmail(dot)com> написал(а):
>
> BTW, I still can't see you're setting deleteXid field of
> ginxlogDeletePage struct anywhere.
Oops. Fixed.
>
> Also, I note that protection against re-usage of recently deleted
> pages is implemented differently than it is in B-tree.
> 1) You check TransactionIdPrecedes(GinPageGetDeleteXid(page),
> RecentGlobalDataXmin)), while B-tree checks
> TransactionIdPrecedes(opaque->btpo.xact, RecentGlobalXmin). Could you
> clarify why do we use RecentGlobalDataXmin instead of RecentGlobalXmin
> here?
As far as I understand RecentGlobalDataXmin may be slightly farther than RecentGlobalXmin in case when replication_slot_catalog_xmin is holding RecentGlobalXmin. And GIN is never used by catalog tables. But let's use RecentGlobalXmin like in B-tree.
> 2) B-tree checks this condition both before putting page into FSM and
> after getting page from FSM. You're checking only after getting page
> from FSM. Approach of B-tree looks better for me. It's seems more
> consistent when FSM pages are really free for usage.
Fixed.
Best regards, Andrey Borodin.
Attachment | Content-Type | Size |
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0001-Stamp-deleted-GIN-page-with-xid-v3.patch | application/octet-stream | 4.1 KB |
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