Re: unlogged tables

On Fri, Dec 10, 2010 at 11:16 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> I think the first patch (relpersistence-v4.patch) is ready to commit,

So I've now committed it.

> and the third patch to allow synchronous commits to become
> asynchronous when it doesn't matter (relax-sync-commit-v1.patch)

Jeff Janes reviewed this, which was good, but he missed a key bit on
which I've now set him straight. So an updated review of this would
be much appreciated.

> doesn't seem to be changing much either, although I would appreciate
> it if someone with more expertise than I have with our write-ahead
> logging system would give it a quick once-over.
>
> The main patch (unlogged-tables-v4.patch) needs more thought.  Right
> now, unlogged buffers are checkpointed, which I want to get rid of.
> Andres Freund suggested we could get by with this and still survive a
> clean shutdown if we fsync() every unlogged relation in the cluster
> before shutting down, but I'm concerned about the case where one of
> the fsync() calls fails.  That's presumably already a problem with
> checkpoints generally, and I haven't traced through the logic to see
> exactly what happens, but I guess this would need similar treatment.
> In a non-shutdown checkpoint, the checkpoint can just fail.  In a
> shutdown checkpoint, we presumably can't just refuse to exit, but it
> shouldn't look like a clean shutdown...

Any input on this point?

--
Robert Haas
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