On Thu, Apr 4, 2019 at 10:47 AM Julien Rouhaud <rjuju...@gmail.com> wrote:
> On Thu, Apr 4, 2019 at 10:25 AM Magnus Hagander <mag...@hagander.net> > wrote: > > > > On Thu, Apr 4, 2019 at 6:22 AM Michael Paquier <mich...@paquier.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. > > Actually we do track counters for shared relations (see > pgstat_report_stat), we just don't expose them in any view. But it's > still possible to get the counters manually: > > # select pg_stat_get_db_blocks_hit(0); > pg_stat_get_db_blocks_hit > --------------------------- > 2710329 > (1 row) > Oh, right, we do actually collect it, we just don't show is. So that's another argument *for* having it in pg_stat_database. Or at least not for having it in a checksum specific view, because then we should really make a separate view for this as well. My main concern is that pg_stat_get_db_numbackends(0) report something > like the total number of backend (though it seems that there's an > extra connection accounted for, I don't know which process it's), so > if we expose it in pg_stat_database, sum(numbackends) won't make sense > anymore. > We could also just hardcoded it so that one always shows 0? >> 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. > > I already added an open item for that. > Good. -- Magnus Hagander Me: https://www.hagander.net/ <http://www.hagander.net/> Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>
