On 2014-02-02 00:04:41 +0900, Michael Paquier wrote: > On Fri, Dec 13, 2013 at 2:47 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > > Andres Freund <and...@2ndquadrant.com> writes: > >> On 2013-12-12 11:55:51 -0500, Tom Lane wrote: > >>> I'm not, however, terribly thrilled with the suggestions to add implicit > >>> casts associated with this type. Implicit casts are generally dangerous. > > > >> It's a tradeof. Currently we have the following functions returning LSNs > >> as text: > >> * pg_current_xlog_location > >> * pg_current_xlog_insert_location > >> * pg_last_xlog_receive_location > >> * pg_last_xlog_replay_location > >> one view containing LSNs > >> * pg_stat_replication > >> and the following functions accepting LSNs as textual paramters: > >> * pg_xlog_location_diff > >> * pg_xlogfile_name > > > >> The question is how do we deal with backward compatibility when > >> introducing a LSN type? There might be some broken code around > >> monitoring if we simply replace the type without implicit casts. > > > > Given the limited usage, how bad would it really be if we simply > > made all those take/return the LSN type? As long as the type's > > I/O representation looks like the old text format, I suspect > > most queries wouldn't notice.
I've asked around inside 2ndq and we could find one single problematic query, so it's really not too bad. > Are there some plans to awaken this patch (including changing the > output of the functions of xlogfuncs.c)? This would be useful for the > differential backup features I am looking at these days. I imagine > that it is too late for 9.4 though... I think we should definitely go ahead with the patch per-se, we just added another system view with lsns in it... I don't have a too strong opinion whether to do it in 9.4 or 9.5. It seems fairly low impact to me, and it's an old patch, but I personally don't have the tuits to refresh the patch right now. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, 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
