Horton

Re: Configuring synchronous replication

Markus Wanner <markus@bluegap.ch>

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From: Markus Wanner <markus@bluegap.ch>
To: Simon Riggs <simon@2ndQuadrant.com>
Cc: Fujii Masao <masao.fujii@gmail.com>, Dimitri Fontaine <dfontaine@hi-media.com>, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>, David Fetter <david@fetter.org>, pgsql-hackers@postgresql.org
Date: 2010-09-22T08:21:10Z
Lists: pgsql-hackers 
Hi,

On 09/21/2010 08:05 PM, Simon Riggs wrote:
> Hmm, no reason? The reason is that the alternative is that the session
> would hang until a standby arrived that offered that level of service.
> Why would you want that behaviour? Would you really request that option?

I think I now agree with Simon on that point. It's only an issue in
multi-master replication, where continued operation would lead to a
split-brain situation.

With master-slave, you only need to make sure your master stays the
master even if the standby crash(es) are followed by a master crash. If
your cluster-ware is too clever and tries a fail-over on a slave that's
quicker to come up, you get the same split-brain situation.

Put another way: if you let your master continue, don't ever try a
fail-over after a full-cluster crash.

Regards

Markus Wanner