On Mon, Jan 10, 2011 at 16:41, Simon Riggs <simon@2ndquadrant.com> wrote:
> On Mon, 2011-01-10 at 17:05 +0200, Heikki Linnakangas wrote:
>> On 10.01.2011 16:49, Simon Riggs wrote:
>> > On Mon, 2011-01-10 at 15:20 +0100, Magnus Hagander wrote:
>> >> On Sun, Jan 9, 2011 at 15:53, Simon Riggs<simon@2ndquadrant.com> wrote:
>> >>> On Sun, 2011-01-09 at 12:52 +0100, Magnus Hagander wrote:
>> >>>
>> >>>> One thing I noticed is that it gives an interesting property to my
>> >>>> patch for streaming base backups - they now show up in
>> >>>> pg_stat_replication, with a streaming location of 0/0.
>> >>>>
>> >>>> If the view is named pg_stat_replication, we probably want to filter
>> >>>> that out somehow. But then, do we want a separate view listing the
>> >>>> walsenders that are busy sending base backups?
>> >>>>
>> >>>> For that matter, do we want an indication that separates a walsender
>> >>>> not sending data from one sending that happens to be at location 0/0?
>> >>>> Most will leave 0/0 really quickly, but a walsender can be idle (not
>> >>>> received a command yet), or it can be running IDENTIFY_SYSTEM for
>> >>>> example.
>> >>>
>> >>> I think we need a status enum. ('BACKUP', 'CATCHUP', 'STREAM') for the 3
>> >>> phases of replication.
>> >>
>> >> That seems reasonable. But if we keep BACKUP in there, should we
>> >> really have it called pg_stat_replication? (yeah, I know, I'm not
>> >> giving up :P)
>> >>
>> >> (You'd need a 4th mode for WAITING or so, to indicate it's waiting for
>> >> a command)
>> >
>> > That's something different.
>> >
>> > The 3 phases are more concrete.
>> >
>> > BACKUP --> CATCHUP<---> STREAM
>> >
>> > When you connect you either do BACKUP or CATCHUP. Once in CATCHUP mode
>> > you never issue a BACKUP. Once we have caught up we move to STREAM. That
>> > has nothing to do with idle/active.
>>
>> So how does a walsender that's waiting for a command from the client
>> show up? Surely it's not in "catchup" mode yet?
>
> There is a trivial state between connect and first command. If you think
> that is worth publishing, feel free. STARTING?
If we don't publish it, it'll implicitly be in one of the others..
Unless we say NULL, of course, but I definitely prefer STARTING then.
--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/
