Understanding the Postgres-XC architecture
Before we dive head-on into Postgres-XC installation and ultimately into configuration, we need to take a deep look at the basic system architecture of this marvelous piece of software, as shown here:
In general, a Postgres-XC system consists of the following essential components:
Data nodes
A Global Transaction Manager (GTM)
A coordinator
A GTM proxy
Let's take a look at the purpose of each of those components.
Data nodes
A data node is the actual storage backbone of the system. It will hold all or a fraction of the data inside the cluster. It is connected to the Postgres-XC infrastructure and will handle the local SQL execution.
GTM
The GTM provides the cluster with a consistent view of the data. A consistent view is necessary because otherwise, it would be impossible to load-balance in an environment that is totally transparent to the application.
A consistent view is provided through a cluster-wide snapshot. In addition to this, the GTM will create Global...
