Re: Checksum errors in pg_stat_database

On Thu, Apr 4, 2019 at 6:22 AM Michael Paquier <michael(at)paquier(dot)xyz> wrote:

> On Wed, Apr 03, 2019 at 11:56:14AM +0200, Julien Rouhaud wrote:
> > But there's still the problem of reporting errors on shared relation,
> > so pg_stat_database doesn't really fit for that. If we go with a
> > checksum centric view, it'd be strange to have some of the counters in
> > another view.
>
> Having pg_stat_database filled with a phantom row full of NULLs to
> track checksum failures of shared objects would be confusing I think.
> I personally quite like the separate view approach, with one row per
> database, but one opinion does not stand as an agreement.
>

It wouldn't be just that, but it would make sense to include things like
blks_read/blks_hit there as well, wouldn't it? As well as read/write time.
Things we don't track today, but it could be useful to do so.

But yeah, I'm not strongly in either direction, so if others feel strongly
a separate view is better, then we should do a separate view.

Anyway, even if we have no agreement on the shape of what we'd like to
> do, I don't think that HEAD is in a proper shape now because we just
> don't track a portion of the objects which could have checksum
> failures. So we should either revert the patch currently committed,
> or add tracking for shared objects, but definitely not keep the code
> in a state in-between.
>

Definitely. That's why we're discussing it now :) Maybe we should put it on
the open items list, because we definitely don't want to ship it one way
and then change our mind in the next version.

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>