Date: Thu, 11 Feb 2010 09:01:18 -0500
From: Aidan Van Dyk <aidan@highrise.ca>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Simon Riggs <simon@2ndQuadrant.com>, Fujii Masao <masao.fujii@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Re: [COMMITTERS] pgsql: Make standby server
	continuously retry  restoring the next WAL
Message-ID: <20100211140118.GB14128@oak.highrise.ca>
References: <20100127152751.3B2047541B9@cvs.postgresql.org>
	<3f0b79eb1002092105r21e009d3v468496058ba04392@mail.gmail.com>
	<4B726120.80007@enterprisedb.com>
	<1265884657.7341.1192.camel@ebony>
	<4B73F678.8070109@enterprisedb.com>
	<1265891248.7341.1346.camel@ebony>
	<4B73FB99.4080403@enterprisedb.com>
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	<4B740613.5090004@enterprisedb.com>
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* Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> [100211 08:29]:
 
> To suppport a restore_command that does the sleeping itself, like
> pg_standby, would require a major rearchitecting of the retry logic. And
> I don't see why that'd desirable anyway. It's easier for the admin to
> set up using simple commands like 'cp' or 'scp', than require him/her to
> write scripts that handle the sleeping and retry logic.

But colour me confused, I'm still not understanding why this is any
different that with normal PITR recovery.

So even with a plain "cp" in your recovery command instead of a
sleep+copy (a la pg_standby, or PITR tools, or all the home-grown
solutions out thery), I'm not seeing how it's going to get "half files".
The only way I can see that is if you're out of disk space in your
recovering pg_xlog.

It's well know in PostgreSQL wal archivne - you don't just "shove" files
into the archive, you make sure they appear there with the right name
atomically.  And if the master is only running the archive command on
whole WAL files, I just don't understand this whole short wal problem.

And don't try and tell me your just "poaching" files from a running
cluster's pg_xlog directory, because I'm going to cry...

a.

-- 
Aidan Van Dyk                                             Create like a god,
aidan@highrise.ca                                       command like a king,
http://www.highrise.ca/                                   work like a slave.

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