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pg_subtrans keeps bloating up in the standby

From: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
To: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Cc: "Kolb, Harald (NSN - DE/Munich)" <harald(dot)kolb(at)nsn(dot)com>
Subject: pg_subtrans keeps bloating up in the standby
Date: 2010-08-27 13:39:21
Message-ID: AANLkTi=x1Uhfatr9OTTXjp2pYLKZpHdFamGKfJYqSw2G@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Hi,

I received the off-list email reporting that pg_subtrans keeps bloating up
in the standby, from Harald (Thanks!). I investigated this issue and found
that the standby doesn't truncate pg_subtrans at all even though HS keeps
extending it. In the master, a checkpoint calls TruncateSUBTRANS() and
truncate old pg_subtrans entries, but in the standby, a restartpoint doesn't
do that. And I found the following comment in CreateRestartPoint():

	/*
	 * Currently, there is no need to truncate pg_subtrans during recovery. If
	 * we did do that, we will need to have called StartupSUBTRANS() already
	 * and then TruncateSUBTRANS() would go here.
	 */

I'm not sure why there is no need to truncate pg_subtrans during recovery.
To fix the issue, we should make a restartpoint call TruncateSUBTRANS().
Thought?

Regards,

-- 
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

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Next:From: Heikki LinnakangasDate: 2010-08-27 14:25:58
Subject: Re: pg_subtrans keeps bloating up in the standby
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Subject: Re: security label support, part.2

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