On 21 March 2017 at 17:32, David Steele <da...@pgmasters.net> wrote: > Hi Thomas, > > On 3/15/17 8:38 PM, Simon Riggs wrote: >> >> On 16 March 2017 at 08:02, Thomas Munro <thomas.mu...@enterprisedb.com> >> wrote: >> >>> I agree that these states exist, but we disagree on what 'lag' really >>> means, or, rather, which of several plausible definitions would be the >>> most useful here. >>> >>> My proposal is that the *_lag columns should always report how long it >>> took for recently written, flushed and applied WAL to be written, >>> flushed and applied (and for the primary to know about it). By this >>> definition, sent LSN = applied LSN is not a special case: we simply >>> report how long that LSN took to be written, flushed and applied. >>> >>> Your proposal is that the *_lag columns should report how far in the >>> past the standby is at each of the three stages with respect to the >>> current end of WAL. By this definition when sent LSN = applied LSN we >>> are currently in the 'A' state meaning 'caught up' and should show >>> 00:00:00. >> >> >> I accept your proposal for how we handle these, on condition that you >> write up some docs that explain the subtle difference between the two, >> so we can just show people the URL. That needs to explain clearly the >> difference in an impartial way between "what is the most recent lag >> measurement" and "how long until we are caught up" as possible >> intrepretations of these values. Thanks. > > > This thread has been idle for six days. Please respond and/or post a new > patch by 2017-03-24 00:00 AoE (UTC-12) or this submission will be marked > "Returned with Feedback".
Thomas, Are you working on another version even? You've not replied to me or David, so its difficult to know what next. Not sure whether this a 6 day lag, or we should show NULL because we are up to date. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
