Re: Enabling Checksums

On Mon, Mar 4, 2013 at 3:13 PM, Heikki Linnakangas
<hlinnakangas(at)vmware(dot)com> wrote:
> On 04.03.2013 20:58, Greg Smith wrote:
>>
>> 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.
>
> This PostgreSQL patch hasn't seen any production use, either. In fact, I'd
> consider btrfs to be more mature than this patch. Unless you think that
> there will be some major changes to the worse in performance in btrfs, it's
> perfectly valid and useful to compare the two.
>
> A comparison with ZFS would be nice too. That's mature, and has checksums.

We've had a few EnterpriseDB customers who have had fantastically
painful experiences with PostgreSQL + ZFS. Supposedly, aligning the
ZFS block size to the PostgreSQL block size is supposed to make these
problems go away, but in my experience it does not have that effect.
So I think telling people who want checksums "go use ZFS" is a lot
like telling them "oh, I see you have a hangnail, we recommend that
you solve that by cutting your arm off with a rusty saw".

There may be good reasons to reject this patch. Or there may not.
But I completely disagree with the idea that asking them to solve the
problem at the filesystem level is sensible.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company