[Postgres-xc-general] newbie - testing and initial setup

[Attila B. <att...@se...>]

Hi,

I have been testing master-master replication solutions recently, and I 
have identified three possible solutions/software:

The scenario
Multiple masters located in different offices in the UK (phase 1); all 
around the globe (phase 2). The servers should be in sync all the time.

Possible solutions
1. Bucardo
2. Postgres-XC
3. EnterpriseDB's xDB Replication Server

Test results
1. Bucardo
Easy to use and set up, but as the data authors at the different offices 
will create and drop tables quite frequently we cannot really cope with 
the administration of bucardo, i.e. adding table to the herds. If you 
have a more or less static dataset or you have a DBA at every site it 
might work for you though.

2. Postgres-XC
The overall structure of the replication looks pretty convincing but I 
have a few question:
- I read somewhere/saw in a slide deck (unfortunately I cannot find it 
any more) that it creates a performance bottleneck to have the 
coordinator and the datanode on the same machine (VMs in my test case). 
Is it still valid?
- Is it possible to add 'slave' datanodes to the DB cluster, e.g an 
external web server?
- Approximate overhead/latency? I guess if the user connects to the 
local (i.e. the user's office) coordinator and commits some changes, the 
user still have to wait for the data to be sync'd with all the datanodes 
in the cluster, right? What if the DB cluser includes 
coordinators/datanodes from all over the globe?

3. EnterpriseDB's xDB Replication Server
TBD

Thanks in advance.

Cheers,
Attila