From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Konstantin Knizhnik <k.knizhnik@postgrespro.ru>
Cc: 曾文旌(义从) <wenjing.zwj@alibaba-inc.com>
Cc: Pavel Stehule <pavel.stehule@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Cc: 蔡松露(子嘉) <zijia@taobao.com>
Cc: Cai, Le <le.cai@alibaba-inc.com>
Cc: 萧少聪(铁庵) <shaocong.xsc@alibaba-inc.com>
Subject: Re: [Proposal] Global temporary tables
Date: Sun, 12 Jan 2020 02:14:01 +0100
Message-ID: <20200112011401.zwvvxoywrrivl542@development> (raw)
In-Reply-To: <f462a08d-288b-3c6b-d55b-136f6b442a61@postgrespro.ru>
References: <CAFj8pRBo8YZ=bJESqf2fkxGL8Bq2Fs7=SjxisS7UhXHh6yPSfA@mail.gmail.com>
<80cf30c2-ebd5-a568-9f62-a970e4d91326@postgrespro.ru>
<5767433E-1A77-4682-B3FD-4869911021C8@alibaba-inc.com>
<6b7570aa-14ea-2f28-c3b5-74dd785bbafe@postgrespro.ru>
<20200105200603.wrb4beacwb57hhpk@development>
<33969545-BEF7-4518-A741-302CBF7FF269@alibaba-inc.com>
<20200106110119.zfrg2m5e2q5mvi5v@development>
<3f360d7b-a46a-79f6-27b6-1b1df8c3ee82@postgrespro.ru>
<20200109163037.u76k3kdr3pcmrytb@development>
<f462a08d-288b-3c6b-d55b-136f6b442a61@postgrespro.ru>
On Fri, Jan 10, 2020 at 03:24:34PM +0300, Konstantin Knizhnik wrote:
>
>
>On 09.01.2020 19:30, Tomas Vondra wrote:
>
>
>>
>>>
>>>>
>>>>>3 Still no one commented on GTT's transaction information
>>>>>processing, they include
>>>>>3.1 Should gtt's frozenxid need to be care?
>>>>>3.2 gtt’s clog clean
>>>>>3.3 How to deal with "too old" gtt data
>>>>>
>>>>
>>>>No idea what to do about this.
>>>>
>>>
>>>I wonder what is the specific of GTT here?
>>>The same problem takes place for normal (local) temp tables, doesn't it?
>>>
>>
>>Not sure. TBH I'm not sure I understand what the issue actually is.
>
>Just open session, create temporary table and insert some data in it.
>Then in other session run 2^31 transactions (at my desktop it takes
>about 2 hours).
>As far as temp tables are not proceeded by vacuum, database is stalled:
>
> ERROR: database is not accepting commands to avoid wraparound data
>loss in database "postgres"
>
>It seems to be quite dubious behavior and it is strange to me that
>nobody complains about it.
>We discuss many issues related with temp tables (statistic, parallel
>queries,...) which seems to be less critical.
>
>But this problem is not specific to GTT - it can be reproduced with
>normal (local) temp tables.
>This is why I wonder why do we need to solve it in GTT patch.
>
Yeah, I think that's out of scope for GTT patch. Once we solve it for
plain temporary tables, we'll solve it for GTT too.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: tomas.vondra@2ndquadrant.com, k.knizhnik@postgrespro.ru, wenjing.zwj@alibaba-inc.com, pavel.stehule@gmail.com, robertmhaas@gmail.com, zijia@taobao.com, le.cai@alibaba-inc.com, shaocong.xsc@alibaba-inc.com
Subject: Re: [Proposal] Global temporary tables
In-Reply-To: <20200112011401.zwvvxoywrrivl542@development>
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