One of the main considerations per Hot Standby vs SLONY is replication scope. With Hot Standby you get everything that occurs in the cluster, across all databases. With SLONY you are limited to at most a single database per "SLONY Cluster", and you can define replication sets which only contain a sub-set of the tables in the database. So, IMHO I'd go with Hot Standby if I wanted to replicate the full cluster and SLONY if I wanted to "slice & dice" tables and target slaves (i.e. replicate all tables for a single db to slave 1, only 50 tables to slave 2, etc...)
--hope this helps
/Kevin
Hi,
Il 09/02/11 01:34, Rangi, Jai ha scritto:
Hello,
I am looking for a replication solution for PG 9.x. Idea is to have one master replication server and multiple (around 20) slave servers read only. I see PG 9 has inbuilt Streaming replication. Is this the best replication solution. How about slony? Which option will keep the slave nodes in closest sync to master and which is more stable.
With PostgreSQL 9.0 in terms of builtin replication you can take advantage of Hot Standby based on either WAL shipping or on Streaming Replication. I would personally stick with builtin solutions if you plan to have full replicas of your databases, even in terms of maintenance and upgrades later on (in the long term). Some tools, including replication manager (repmgr) are coming out in order to manage HA clusters (for more info:
http://blog.2ndquadrant.com/en/2011/01/easier-postgresql-90-clusters.html).
Cheers,
Gabriele
-- Gabriele Bartolini - 2ndQuadrant ItaliaPostgreSQL Training, Services and Supportgabriele.bartolini@2ndQuadrant.it | www.2ndQuadrant.it