Re: [Postgres-xc-general] JDBC driver for 0.9.4

[Michael P. <mic...@gm...>]

On Mon, May 30, 2011 at 7:34 PM, Lionel Frachon <lio...@gm...>wrote:

> Hi again,
>
> I turned off connection pooling on coordinator (dunno why it sayed
> on), raised the shared_buffers of coordinator, allowed 1000
> connections and the error disappeared.
>
I am not really sure I get the meaning of this, but how did you turn off
pooler on coordinator.
Did you use the parameter persistent_connections?
Connection pooling from coordinator is an automatic feature and you have to
use it if you want to connect from a remote coordinator to backend XC nodes.

You also have to know that it is important to set a limit of connections on
datanodes equal to the sum of max connections on all coordinators.
For example, if your cluster is using 2 coordinator with 20 max connections
each, you may have a maximum of 40 connections to datanodes.
This uses a lot of shared buffer on a node, but typically this maximum
number of connections is never reached thanks to the connection pooling.

Please node also that number of Coordinator <-> Coordinator connections may
also increase if DDL are used from several coordinators.

However, all data is still going on one node (and whatever I could
> choose as primary datanode), with 40 warehouses... any specific syntax
> to load balance warehouses over nodes ?
>

CREATE TABLE foo (column_key type, other_column int) DISTRIBUTE BY
HASH(column_key);
-- 
Michael Paquier
http://michael.otacoo.com