Re: Time based lag tracking for logical replication

On Mon, May 08, 2017 at 10:30:45PM -0700, Noah Misch wrote:
> On Fri, May 05, 2017 at 07:07:26AM +0000, Noah Misch wrote:
> > On Wed, May 03, 2017 at 08:28:53AM +0200, Simon Riggs wrote:
> > > On 23 April 2017 at 01:10, Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com> wrote:
> > > > Hi,
> > > >
> > > > The time based lag tracking commit [1] added interface for logging
> > > > progress of replication so that we can report lag as time interval
> > > > instead of just bytes. But the patch didn't contain patch for the
> > > > builtin logical replication.
> > > >
> > > > So I wrote something that implements this. I didn't like all that much
> > > > the API layering in terms of exporting the walsender's LagTrackerWrite()
> > > > for use by plugin directly. Normally output plugin does not have to care
> > > > if it's running under walsender or not, it uses abstracted write
> > > > interface for that which can be implemented in various ways (that's how
> > > > we implement SQL interface to logical decoding after all). So I decided
> > > > to add another function to the logical decoding write api called
> > > > update_progress and call that one from the output plugin. The walsender
> > > > then implements that new API to call the LagTrackerWrite() while the SQL
> > > > interface just does not implement it at all. This seems like cleaner way
> > > > of doing it.
> > > >
> > > > Thoughts?
> > >
> > > Agree cleaner.
> > >
> > > I don't see any pacing or comments about it, nor handling of
> > > intermediate messages while we process a large transaction.
> > >
> > > I'll look at adding some pacing code in WalSndUpdateProgress()
> >
> > [Action required within three days.]
> >
> > Simon, I understand, from an annotation on the open items list, that you have
> > volunteered to own this item. Please observe the policy on open item
> > ownership[1] and send a status update within three calendar days of this
> > message. Include a date for your subsequent status update. Testers may
> > discover new open items at any time, and I want to plan to get them all fixed
> > well in advance of shipping v10. Consequently, I will appreciate your efforts
> > toward speedy resolution. Thanks.
> >
> > [1] https://www.postgresql.org/message-id/20170404140717.GA2675809%40tornado.leadboat.com
>
> This PostgreSQL 10 open item is past due for your status update. Kindly send
> a status update within 24 hours, and include a date for your subsequent status
> update. Refer to the policy on open item ownership:
> https://www.postgresql.org/message-id/20170404140717.GA2675809%40tornado.leadboat.com

IMMEDIATE ATTENTION REQUIRED. This PostgreSQL 10 open item is long past due
for your status update. Please reacquaint yourself with the policy on open
item ownership[1] and then reply immediately. If I do not hear from you by
2017-05-11 06:00 UTC, I will transfer this item to release management team
ownership without further notice.

[1] https://www.postgresql.org/message-id/20170404140717.GA2675809%40tornado.leadboat.com