To: Simon Riggs <simon@2ndQuadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>,
	Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>,
	ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp>,
	pgsql-hackers@postgresql.org
Subject: Re: rmgr hooks and contrib/rmgr_hook
In-Reply-To: <1221485063.3913.1350.camel@ebony.2ndQuadrant> (Simon Riggs's
	message of "Mon\, 15 Sep 2008 14\:24\:23 +0100")
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References: <20080901121833.4A18.52131E4D@oss.ntt.co.jp>
	<1220345064.4371.275.camel@ebony.2ndQuadrant>
	<20080902174613.76B2.52131E4D@oss.ntt.co.jp>
	<1220348980.4371.316.camel@ebony.2ndQuadrant>
	<14451.1220369969@sss.pgh.pa.us>
	<1220372673.4371.465.camel@ebony.2ndQuadrant>
	<48CB72C8.1070700@enterprisedb.com>
	<1221470800.3913.1229.camel@ebony.2ndQuadrant>
	<87sks1oi4o.fsf@oxford.xeocode.com> <24006.1221483138@sss.pgh.pa.us>
	<1221485063.3913.1350.camel@ebony.2ndQuadrant>
From: Gregory Stark <stark@enterprisedb.com>
Organization: EnterpriseDB
Date: Mon, 15 Sep 2008 14:58:50 +0100
Message-ID: <87y71tmrxh.fsf@oxford.xeocode.com>
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Simon Riggs <simon@2ndQuadrant.com> writes:

> The version mismatch idea presumes that a code author would structure
> their code in two pieces: one to generate the WAL and one to read it.
> Seems much more likely to me that authors would have one module
> containing both as a way of avoiding the problem altogether. So I'm not
> sure what to check, and against what?

No, the danger is that someone generates a backup with one version of the
plugin and then restores with a different version of the plugin.

That would be frightfully easy to do when doing a minor upgrade, for example.
Or on a standby database if you've installed a new version of the plugin since
the standby was built.

-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com
  Ask me about EnterpriseDB's PostGIS support!