On Tue, 2008-07-22 at 18:37 +0200, Markus Wanner wrote: > Simon Riggs wrote: > > * Logical replication via transaction log > > * Integration with synchronous replication > > I'm curious on what you mean by these two points. AFAIK you are speaking > of "logical" replication for methods which don't rely on the internal > storage format of the database, but instead replicate closer to the SQL > level. But the transaction log (the XLOG for Postres, REDO log for > Oracle, etc..) is certainly bound to the storage format, so I'd classify > the log shipping approaches as "physical" replication. What is it you > are talking about?
Reconstructing SQL from WAL, allowing logical apply. So yes, you're right, the actual replication of the data from one node to another is physical - its the final apply of the changes that is logical. So this fits neatly with our commitment to put synchronous replication into server. It allows WAL to be used as the replication transport, which reduces the impact of tracking changes via triggers. The presence of commit records in the sequence can be used to parallelize the apply phase if required. I'm proposing to put the mechanisms in place to allow WAL to be used by other replication projects. Which turn out to be relatively small changes to the main server. -- 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
