Understand the default cluster configuration

The Bitnami Multi-Tier Solution for PostgreSQL uses multiple VMs, consisting of 1 primary and 1 or more replicas, to provide a horizontally scalable and fault-tolerant deployment. Data automatically replicates from the primary node to all replicas. PostgreSQL server is configured to listen for connections from any IP address (0.0.0.0).

To understand how it works, consider the example below of a two-node cluster (one primary and one replica):

• On the primary node, create a new table and populate it with some data:

    postgres=# \c bitnami
    You are now connected to database "bitnami" as user "postgres".
  
    bitnami=# CREATE TABLE test (id INT NOT NULL, value VARCHAR(255) NOT NULL);
    CREATE TABLE
  
    bitnami=# INSERT INTO test VALUES (1, 'foo'), (2, 'bar');
    INSERT 0 2
  

• On any of the replica nodes, check if the table exists and list its contents. It should display the same data originally entered on the primary node:

    postgres=# \c bitnami
    You are now connected to database "bitnami" as user "postgres".
  
    bitnami=# select * from test;
     id | value
    ----+-------
      1 | foo
      2 | bar
    (2 rows)
  

This shows that records added on the primary node are automatically replicated to the replica(s). For more information, refer to the PostgreSQL documentation on replication.