On Thu, Dec 3, 2015 at 1:00 PM, Craig Ringer <cr...@2ndquadrant.com> wrote: > On 3 December 2015 at 04:22, Julian Schauder <julian.schau...@credativ.de> > wrote: > >> >> I suggest adding a new state to pg_stat_activity.state for backends that >> are >> >> waiting for their synchronous commit to be flushed on the remote host. >> > > Excellent idea. Anything that improves management and visibility into what > the system is doing like this is really valuable. > > I notice that you don't set the 'waiting' flag. 'waiting' is presently > documented as: > > <entry>True if this backend is currently waiting on a lock</entry> > > ... but I'm inclined to just widen its definition and set it here, since we > most certainly are waiting, and the column isn't named 'waiting_on_a_lock'. > It shouldn't upset various canned lock monitoring queries people have since > they generally do an inner join on pg_locks anyway. > > There are no test changes in this patch, but that's reasonable because we > don't currently have a way to automate tests of sync rep. > > I've attached a patch with minor wording/formatting changes, but I think I'd > like to change 'waiting' to true as well. Opinions?
A couple of minor things I noticed: + <literal>waiting for synchronous replication</>: The backend is waiting for its transaction to be flushed on a synchronous standby. I wouldn't say "flushed" here. If you set synchronous_commit = remote_write, then it's not actually waiting for it to be flushed (and there may eventually be other levels too). Maybe just "The backend is waiting for a response from a synchronous standby"? +#include <pgstat.h> I think this should use "" instead of <> and should come after #include "miscadmin.h". Thinking of other patches in flight, I think I'd want the proposed N-sync standbys feature to be able to explain in more detail what it's waiting for (and likewise my causal reads proposal which does that via the process title), though I realise that the details of how/where to do that are changing in the "replace pg_stat_activity.waiting" thread which this patch is waiting on. -- Thomas Munro http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
