Much thanks to everyone! The mailing list, as usual, has been extremely helpful.
On Mon, Sep 20, 2010 at 10:33 AM, Brad Nicholson <bnich...@ca.afilias.info>wrote: > On 10-09-20 12:49 PM, Bruce Momjian wrote: > >> John Cheng wrote: >> >>> Congrats on the 9.0 release of PostgreSQL. One of the features I am >>> really >>> interested in is the built-in binary replication. >>> >>> Our production environment has been using PostgreSQL for more than 5 >>> years >>> (since this project started). We have been using Slony-I as our >>> replication >>> mechanism. I am interested to find out the pros and cons of Slony vs the >>> built-in replication in 9.0. Based on what I understand: >>> >>> * Slony has a higher overhead than the binary replication in 9.0 >>> * When using Slony, schema change must be applied via slonik (in most >>> cases) >>> * Unfortunately, IMO it is easy to make a mistake when applying schema >>> changes in Slony, fortunately, it is easy to drop and recreate the >>> replication sets >>> * Slony is an asynchronous replication mechanism >>> * Slony allows you to replication some tables, while ignoring others >>> >>> * PostgreSQL 9.0 with hot standby& streaming replication is an >>> asynchronous >>> replication mechanism >>> * Overhead is low compared to Slony >>> >>> Are there some cases where it is better to use Slony, for example, when >>> you >>> must specifically exclude tables from replication? I believe our system >>> will >>> be better off using the built-in replication mechanism of 9.0, and I am >>> guessing most people will be in the same boat. >>> >> You have summarized the differences well. Streaming replication has >> lower overhread, but doesn't allow per-table granularity or allow >> replication between different versions of Postgres. >> >> > Slony will also allow you to: > > -run custom schema (like extra indexes) on replicas > -replicate between different hardware architectures and OS's > -run lengthy queries against replicas having to worry about trade offs > surrounding query cancellation vs standby lagging. > -switch roles of two nodes without entering a degraded state or worrying > about STONITH. If you switch roles in a controlled manner, both nodes > remain in the cluster. Slony prevents writes against the replica. > > I do agree that for most, Slony is overkill and streaming replication and > hot standby will be the better choice. > > -- > Brad Nicholson 416-673-4106 > Database Administrator, Afilias Canada Corp. > > > > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > -- --- John L Cheng
