Re: Sync Rep for 2011CF1

On Wed, Feb 9, 2011 at 3:53 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> That having been said, there is at least one part of this patch which
> looks to be in pretty good shape and seems independently useful
> regardless of what happens to the rest of it, and that is the code
> that sends replies from the standby back to the primary.  This allows
> pg_stat_replication to display the write/flush/apply log positions on
> the standby next to the sent position on the primary, which as far as
> I am concerned is pure gold.  Simon had this set up to happen only
> when synchronous replication or XID feedback in use, but I think
> people are going to want it even with plain old asynchronous
> replication, because it provides a FAR easier way to monitor standby
> lag than anything we have today.  I've extracted this portion of the
> patch, cleaned it up a bit, written docs, and attached it here.

What about also sending back the timestamp of the last applied
transaction? That's more user-friendly than the apply location
when we calculate the lag of replication, I think.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center