Re: Keepalive for max_standby_delay - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: Keepalive for max_standby_delay
Date
Msg-id 1274217705.28911.3922.camel@ebony
Whole thread Raw
In response to Re: Keepalive for max_standby_delay  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
List pgsql-hackers
On Tue, 2010-05-18 at 17:08 -0400, Heikki Linnakangas wrote:
> On 17/05/10 12:36, Jim Nasby wrote:
> > On May 15, 2010, at 12:05 PM, Heikki Linnakangas wrote:
> >> What exactly is the user trying to monitor? If it's "how far behind is
> >> the standby", the difference between pg_current_xlog_insert_location()
> >> in the master and pg_last_xlog_replay_location() in the standby seems
> >> more robust and well-defined to me. It's a measure of XLOG location (ie.
> >> bytes) instead of time, but time is a complicated concept.
> >
> > I can tell you that end users *will* want a time-based indication of how far behind we are. DBAs will understand
"we'rethis many transactions behind", but managers and end users won't. Unless it's unreasonable to provide that info,
weshould do so.
 
> 
> No doubt about that, the problem is that it's hard to provide a reliable 
> time-based indication.

I think I have one now.

-- Simon Riggs           www.2ndQuadrant.com



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