On Tue, 2008-08-12 at 11:52 -0400, Bruce Momjian wrote: > Simon Riggs wrote: > > > > On Sat, 2008-07-26 at 10:17 +0200, Markus Wanner wrote: > > > What I still don't understand is, why you are speaking about > > > "logical" > > > replication. It rather sounds like an ordinary log shipping approach, > > > where the complete WAL is sent over the wire. Nothing wrong with > > > that, > > > it certainly fits many needs and I welcome such a solution for > > > Postgres. > > > > Yes, first stage is log shipping. Second stage is either physical or > > logical apply. > > What is the attraction of logical application of the WAL logs? > Transmitting to a server with different architecture?
Yes, * different release * different encoding * different CPU architecture * (with the correct transform) a different DBMS So logical apply can provide a route for data transfer between applications, not just replication for DR or HA. Physical apply works and will be more performant, but it will always be more restrictive. So there are arguments for doing it both ways. I believe that we can and should offer both options to provide customer choice. Ideally, it would be nice to be able to switch between the two without significant reconfiguration, but that's definitely not for this release. (Pragmatically, implementation will be limited by my funding.) -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
