Re: [Postgres-xc-general] General config/arch questions

[Abbas B. <abb...@te...>]

On Fri, Mar 4, 2011 at 8:06 PM, Lionel Frachon <lio...@gm...>wrote:

> Hello,
>
> I'm starting an evaluation of the cluster (not having any PG
> background, but Oracle & MySql for years...), and some questions
> appear to me after reading the doc, any help appreciated.
>

Thank you, I would suggest playing around with plain PG first. That would
help you a lot.


>
> My actual setup is :
> pgxc1 for GTM, Coordinator and datanode
> pgxc2 for datanode only
>

You mean you will have 2 computers, one will run GTM, Coordinator and 1st
datanode and the other the 2nd data node. If yes then this would be fine.

BTW what Linux distribution will you be using?

Please remember that for the first time gtm has to be started with -x option
and it is better to start gtm before you initdb for the coordinator and the
2 data nodes. For successive runs you should skip -x option. As a general
rule you should always start gtm first then the data nodes and then
the coordinator.


> 1.General : Is a coordinator needed for each node, or one coordinator
> 'to rule them all' can be setup ?
>

Yes, one coordinator serve multiple data nodes.


>
> 2. Configuration :  What should be the differences between
> postgresql.conf in /datanode and /coordinator, if there are any ?


Yes each node in the cluster has to have a unique node ID, that is picked
from the postgresql.conf.
The coordinator needs to know the number of data nodes, and info required to
to connect to them e.g. user name password etc
Other than that I don't remember any thing on top of my head.
Please take a look at the portions in the conf file specific to the XC, that
would help.


> Some
> portions are they ignored for a specific function (ex : coordinator vs
> datanode config, etc...)
> In this can pg_hba.conf & postgresql.conf be shared for the same
> server (maybe using symbolic links...)
>

No, as I explained earlier.


>
> 3. GTM : I get on second node an "WARNING:  Do not have a GTM snapshot
> available", can this be related to previous config files/setup  ?
>

For the first data node the default configuration of a localhost GTM would
be fine but for the 2nd data node you need to tell the data node where GTM
is located, for this you need to change the gtm_host parameter in the
postgresql.conf file of the 2nd datanode to the IP addeess of your first
computer (which runs GTM).


>
> 4. Administration : are there ways of getting the online status of the
> nodes from one node to another
>

This is currently under development. I can provide you details later.


>
> Thanks
>
> Lionel F.
>
>
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