Re: Strange replication problem - segment restored from archive but still requested from master - Mailing list pgsql-general

From Guillaume Lelarge
Subject Re: Strange replication problem - segment restored from archive but still requested from master
Date
Msg-id CAECtzeUn1b=YAJweHqQoT7ATBzi7r3JyF2VuG8Qp-Ut2X=Mm4w@mail.gmail.com
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In response to Re: Strange replication problem - segment restored from archive but still requested from master  (Piotr Gasidło <quaker@barbara.eu.org>)
Responses Re: Strange replication problem - segment restored from archive but still requested from master
List pgsql-general
2015-05-22 18:36 GMT+02:00 Piotr Gasidło <quaker@barbara.eu.org>:
2015-05-22 6:55 GMT+02:00 Fujii Masao <masao.fujii@gmail.com>:
>
> This problem happens when WAL record is stored in separate two WAL files and
> there is no valid latter WAL file in the standby. In your case, the former file
> is 0000000400004C4D00000090 and the latter is 0000000400004C4D00000091.
>
> In this case, the first half of WAL record can be read from the former WAL file,
> but the remaining half not because no valid latter file exists in the standby.
> Then the standby tries to retrieve the latter WAL file via replication.
> The problem here is that the standby tries to start the replication from the
> starting point of WAL record, i.e., that's the location of the former WAL file.
> So the already-read WAL file is requested via replication.
> (..)

I currently have wal_keep_segments set to 0.
Setting this to higher value will help? As I understand: master won't
delete segment and could stream it to slave on request - so it will
help.

It definitely helps, but the issue could still happen.
 
Does this setting delays WAL archiving?


Nope. It delays recycling.


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