Robert Haas wrote: > On Wed, Jul 6, 2016 at 6:06 PM, Andres Freund <and...@anarazel.de> wrote: > > Hm. We can't easily do that in the back-patched version; because a > > standby won't know to check for the flag . That's kinda ok, since we > > don't yet need to clear all-visible yet at that point of > > heap_update. But that better means we don't do so on the master either. > > Is there any reason to back-patch this in the first place?
Wasn't this determined to be a pre-existing bug? I think the probability of occurrence has increased, but it's still possible in earlier releases. I wonder if there are unexplained bugs that can be traced down to this. I'm not really following this (sorry about that) but I wonder if (in back branches) the failure to propagate in case the standby wasn't updated can cause actual problems. If it does, maybe it'd be a better idea to have a new WAL record type instead of piggybacking on lock tuple. Then again, apparently the probability of this bug is low enough that we shouldn't sweat over it ... Moreso considering Robert's apparent opinion that perhaps we shouldn't backpatch at all in the first place. In any case I would like to see much more commentary in the patch next to the new XLHL flag. It's sufficiently different than the rest than it deserves so, IMO. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers