>> Because the KnownAssignedXIDs and lock tables on the standby need to >> be large enough to contain the largest snapshot and greatest number of >> AccessExclusiveLocks that could exist on the master at any given time. > > Right. Initially during the development of Hot Standby, it looked like > the "max_connections >= master's" requirement on standbys wasn't going > to be necessary, or could be avoided. However, Simon gave up on that > idea on pragmatic grounds here: > > http://www.postgresql.org/message-id/1252002165.2889.467.camel@ebony.2ndQuadrant > > I'd thought about revisiting this myself, but I think that the impetus > to do so is lessened by recent work on logical replication. >
Hi Peter Your information make my question be clearly. I understand the discussions about this restriction. Thanks. 2013/12/12 Peter Geoghegan <p...@heroku.com> > On Tue, Dec 10, 2013 at 1:17 PM, Robert Haas <robertmh...@gmail.com> > wrote: > > Because the KnownAssignedXIDs and lock tables on the standby need to > > be large enough to contain the largest snapshot and greatest number of > > AccessExclusiveLocks that could exist on the master at any given time. > > Right. Initially during the development of Hot Standby, it looked like > the "max_connections >= master's" requirement on standbys wasn't going > to be necessary, or could be avoided. However, Simon gave up on that > idea on pragmatic grounds here: > > > http://www.postgresql.org/message-id/1252002165.2889.467.camel@ebony.2ndQuadrant > > I'd thought about revisiting this myself, but I think that the impetus > to do so is lessened by recent work on logical replication. > > -- > Peter Geoghegan >
