Re: Re: [bug fix] Cascading standby cannot catch up and get stuck emitting the same message repeatedly

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Re: [bug fix] Cascading standby cannot catch up and get stuck emitting the same message repeatedly
Date: 2016-11-24 03:51:44
Message-ID: CAA4eK1LTve7TU13gBk-YN5KJUA8EMii7_UcpUCPQMwxG8ij2PA@mail.gmail.com
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On Tue, Nov 22, 2016 at 8:48 AM, Tsunakawa, Takayuki
<tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> wrote:
> From: pgsql-hackers-owner(at)postgresql(dot)org
>
> If the problem occurs, the following pair of lines appear in the server log of the cascading standby. Could you check it?
>
> LOG: restored log file "000000020000000000000003" from archive
> LOG: out-of-sequence timeline ID 1 (after 2) in log file 0, segment 3, offset 0
>

Thanks for the clarification, I could reproduce the issue and confirms
that patch has fixed it. Find logs of cascading standby at PG9.2
Head and Patch attached (I have truncated few lines at end of server
log generated in Head as those were repetitive). I think the way you
have directly explained the bug steps in code comments is not right
(think if we start writing bug steps for each bug fix, how the code
will look like). So I have modified the comment to explain the
situation and reason of check, see if you find that as okay?

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Attachment Content-Type Size
postgresql_Thu_Patch.log application/octet-stream 3.4 KB
postgresql_Thu_Head.log application/octet-stream 12.0 KB
cascading_standby_stuck_v3.patch application/octet-stream 4.8 KB

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