Re: [HACKERS] Infrastructure changes for recovery

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: List pgsql-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: [HACKERS] Infrastructure changes for recovery
Date: 2008-09-10 21:06:37
Message-ID: 1221080797.3913.768.camel@ebony.2ndQuadrant
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On Mon, 2008-09-08 at 13:34 -0400, Tom Lane wrote:

> ISTM that it would probably be better if there were exactly one InRedo
> flag in shared memory, probably in xlog.c's shared state, with the
> postmaster not being responsible for setting or clearing it; rather
> the startup process should do those things.


> > * bgwriter and stats process starts in consistent recovery mode.
> > bgwriter changes mode when startup process completes.
> I'm not sure about the interaction of this. In particular, what about
> recovery restart points before we have reached the safe stop point?
> I don't think we want to give up the capability of having those.
> Also, it seems pretty bogus to update the in-memory ControlFile
> checkpoint values before the restart point is actually done. It looks
> to me like what you have done is to try to use those fields as signaling
> for the restart request in addition to their existing purposes, which
> I think is confusing and probably dangerous. I'd rather there were a
> different signaling path and ControlFile maintains its currrent
> definition.


Testing takes a while on this, I probably won't complete it until
Friday. So enclosed patch is for eyeballs only at this stage.

I added in the XLogCtl padding we've discussed before, while I'm there.

Simon Riggs
PostgreSQL Training, Services and Support

Attachment Content-Type Size
recovery_infrastruc.v3.patch text/x-patch 37.6 KB

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