[Postgres-xl-developers] Postgres XL and Npgsql: Coordinator Exception

Jaaromy Zierse jzierse at ghostery.com
Wed Apr 8 16:25:36 PDT 2015

I am getting the following error when using Npgsql to execute any statement
against any of my Postgres XL coordinators:

*ERROR: XX000: Could not begin transaction on data node.*

Connecting via pgAdmin III and executing a query against the coordinators
successfully executes and distributes the data.

Strangely, if I connect directly to the Datanodes using Npgsql, then the
statements execute successfully.

Here is an example of the Npgsql code:

using (var connection = new NpgsqlConnection(connectionString))

	using (var command = connection.CreateCommand())
		command.CommandText = @"SET TRANSACTION READ
WRITE;														INSERT INTO test_table(														id,
name)														VALUES (1, 'Rando');";


Below is a description of our cluster configuration:

Postgres XL Components: GTM and GTM Proxy

Server: DEV-PG1
Postgres XL Components: Coordinator 1 (Coord1) and Datanode1 (Datanode1)

Server: DEV-PG2
Postgres XL Components: Coordinator 2 (Coord2) and Datanode2 (Datanode2)

Server: DEV-PG1
Postgres XL Components: Coordinator 1 (Coord3) and Datanode3 (Datanode3)

All coordinators run on port 5432 and all datanodes run on port 15432.

The GTM is using port 6666 and the GTM Proxy is using port 6668.

Thank you.
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