[Postgres-xc-general] Some questions about postgres-XC

[Yehezkel H. <hor...@ch...>]

First I want to thank you all for this project, it seems very interesting, involving highly sophisticated technology and answering a real need of the industry.

Second, I allow myself suggest you to consider some conventions for your mailing list (as example cUrl's Etiquette:  http://curl.haxx.se/mail/etiquette.html) as it is quite hard to follow threads in the archive.

My goal - I have an application that needs SQL DB and must always be up (I have a backup machine for this purpose).
I plan to deploy as follow:
Machine A: 1 Datanode, 1 Coordinator, 1 GTM proxy, 1 GTM
Machine B: 1 Datanode, 1 Coordinator, 1 GTM proxy, 1 GTM-slave
Both machines have my application installed on, and the clients of my application will connect to the working machine (in normal case, they can connect to either one of them with simple load-balancer, hence I need multi-mater replication).

If I understand correctly, in case of failure in Machine A, I need to promote the GTM-slave to become GTM master, and reconnect the GTM proxy - all this could be done in Machine B. Right?

My questions:

1.       In your docs, you always put the GTM in dedicated machine.

a.       Is this a requirement, just an easy to understand topology or best practice?

b.      In case of best practice, what is the expected penalty in case the GTM is deployed on the same machine with coordinator and datanode?

c.       In such deployment, is there a need for GTM proxy on this machine?

2.       What should I do after Machine A is back to life if I want:

a.       Make it act as a new slave?

b.      Make it become the master again?

I saw this question in the archive (http://sourceforge.net/p/postgres-xc/mailman/message/31302978/), but didn't found any answer:
> I suppose my question is: what do I need to do, to make the former masters
> into new slaves?  To me it would make sense to be able to failover node1
> once and then again, and be left with more or less the same configuration
> as in the beginning.  It would be okay if there is some magic command I can
> run to reconfigure a former master as the new slave.

Hope I don't ask silly questions, but I couldn't find answers in the docs/archive.

Thanks in advanced

Yehezkel Horowitz
Check Point Software Technologies Ltd.