On 6/1/07, Jeff Davis <pgsql@xxxxxxxxxxx> wrote:
On Fri, 2007-06-01 at 17:00 +0200, Alexander Staubo wrote: > the projected Slony-II design, but the setup seems dead simple, and > from the docs I have found it seems to transparently replicate schema > changes, unlike Slony-I. So that's something. To be fair to Slony-I, the fact that it does not replicate DDL is a feature, not a bug. It's table-based, which is a very flexible design.
I fail to see how that's an excuse not to replicate DDL. If I run "alter table" on the master, there is no reason whatever that this command cannot be executed on all the slaves -- which is what I would expect of a replication system. To put it differently: A slave's table is a replica of the master's table; if I alter the master table, and the slave is not updated to reflect this change, then the slave table is no longer a true replica, and the system has failed its core purpose, that of *replicating*. I could be wrong, but I believe Slony fails at this because it is trigger-based and simply cannot detect DDL changes. Alexander.
