Re: Enabling Checksums

On 3/4/13 2:11 AM, Simon Riggs wrote:
> It's crunch time. Do you and Jeff believe this patch should be
> committed to Postgres core?

I want to see a GUC to allow turning this off, to avoid the problem I
saw where a non-critical header corruption problem can cause an entire
page to be unreadable. A variation on that capable of turning this off
altogether, as Craig suggested, is a good idea too.

Those are both simple fixes, and I would be pleased to see this
committed at that point.

I'll write up a long discussion of filesystem trends and why I think
this is more relevant than ever if that's the main objection now. There
is no such thing as a stable release of btrfs, and no timetable for when
there will be one. I could do some benchmarks of that but I didn't
think they were very relevant. Who cares how fast something might run
when it may not work correctly? btrfs might as well be /dev/null to me
right now--sure it's fast, but maybe the data won't be there at all.
How long has it taken the Linux kernel to reach the point it handles
write barriers and fsync correctly? It does not give me a lot of
confidence that now is the time they'll suddenly start executing on
database filesystem mechanics perfectly.

--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com