Message-ID: <4BAB3571.8070001@enterprisedb.com>
Date: Thu, 25 Mar 2010 12:05:37 +0200
From: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Organization: EnterpriseDB
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To: Simon Riggs <simon@2ndQuadrant.com>
CC: Fujii Masao <masao.fujii@gmail.com>, Aidan Van Dyk <aidan@highrise.ca>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Re: [COMMITTERS] pgsql: Make standby server  continuously
	retry restoring the next WAL
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Simon Riggs wrote:
> On Thu, 2010-03-25 at 11:08 +0900, Fujii Masao wrote:
>> And if the trigger file is
>> found, I think that the startup process should emit a FATAL, i.e., the
>> server should exit immediately, to prevent the server from becoming the
>> primary in a half-finished state. 
> 
> Please remember that "half-finished" is your judgment on what has
> happened in the particular scenario you are considering. In many cases,
> an invalid WAL record clearly and simply indicates the end of WAL and we
> should start up normally.

Not in the archive. An invalid WAL record in a file in pg_xlog is
usually an indication of end-of-WAL, but there should be no invalid
records in the archived WAL files, or streamed from the master.

> "State" is a good word here. I'd like to see the server have a clear
> state model with well documented transitions between them. The state
> should also be externally queriable, so we can work out what its doing
> and how long we can expect it to keep doing it for.

Agreed.

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