Re: corrupt pages detected by enabling checksums

On 2013-04-04 17:39:16 -0700, Jeff Davis wrote:
> On Thu, 2013-04-04 at 22:39 +0200, Andres Freund wrote:
> > I don't think its really slower. Earlier the code took WalInsertLock
> > everytime, even if we ended up not logging anything. Thats far more
> > epensive than a single spinlock. And the copy should also only be taken
> > in the case we need to log. So I think we end up ahead of the current
> > state.
>
> Good point.
>
> > > The code looks good to me except that we should be consistent about the
> > > page hole -- XLogCheckBuffer is calculating it, but then we copy the
> > > entire page. I don't think anything can change the size of the page hole
> > > while we have a shared lock on the buffer, so it seems OK to skip the
> > > page hole during the copy.
> >
> > I don't think it can change either, but I doubt that there's a
> > performance advantage by not copying the hole. I'd guess the simpler
> > code ends up faster.
>
> I was thinking more about the WAL size, but I don't have a strong
> opinion.

I was just a bit dense. No idea what I missed there.

How does the attached version look? I verified that it survives
recovery, but not more.

Jeff, any chance you can run this for a round with your suite?

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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