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From: Heikki Linnakangas <[email protected]>
To: Alvaro Herrera <[email protected]>
Cc: Simon Riggs <[email protected]>
Cc: Fujii Masao <[email protected]>
Cc: Aidan Van Dyk <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Subject: Re: Re: [COMMITTERS] pgsql: Make standby server continuously retry restoring the next WAL
Date: Fri, 19 Mar 2010 15:44:53 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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Alvaro Herrera wrote:
> Heikki Linnakangas escribió:
> 
>> When recovery reaches an invalid WAL record, typically caused by a
>> half-written WAL file, it closes the file and moves to the next source.
>> If an error is found in a file restored from archive or in a portion
>> just streamed from master, however, a PANIC is thrown, because it's not
>> expected to have errors in the archive or in the master.
> 
> Hmm, I think I've heard that tools like walmgr do incremental copies of
> the current WAL segment to the archive.  Doesn't this change break that?

Hmm, you could have a restore_command that checks the size before
restoring to make it still work. I note that pg_standby does that, but
of course you can't use pg_standby with the built-in standby mode. Or
maybe we should modify the built-in standby mode to handle partial files
coming from restore_command by not throwing an error but recovering to
the end of the partial file, and then retrying restore_command again
with the same filename until the whole file is recovered (or the missing
WAL is received through other means, ie. streaming replication).

-- 
  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com

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