Cloudera Docs

Configure the PostgreSQL server

By default, PostgreSQL only accepts connections on the loopback interface. You must reconfigure PostgreSQL to accept connections from the fully qualified domain names (FQDN) of the hosts hosting the services for which you are configuring databases. If you do not make these changes, the services cannot connect and use the database on which they depend.

  1. Make sure that LC_ALL is set to en_US.UTF-8 and initialize the database as follows: 
    echo 'LC_ALL="en_US.UTF-8"' >> /etc/locale.conf
sudo su -l postgres -c "postgresql-setup initdb"
  2. Enable MD5 authentication. Edit the pg_hba.conf file typically located at /var/lib/pgsql/data or /etc/postgresql/[***VERSION***]>/main. Add the following line: 
    host all all 127.0.0.1/32 scram-sha-256
  3. If the default pg_hba.conf file contains the "host all all 127.0.0.1/32 ident" line, then the host line specifying MD5 authentication shown above must be inserted before this line. Failure to do so may cause an authentication error when running the scm_prepare_database.sh script. You can modify the contents of the MD5 line shown above to support different configurations. For example, if you want to access PostgreSQL from a different host, replace 127.0.0.1 with your IP address and update the postgresql.conf file, which is typically found in the same place as pg_hba.conf, to include the following line: 
    listen_addresses = '*'
  4. Configure settings to ensure your system performs as expected. Update these settings in the /var/lib/pgsql/data/postgresql.conf or /var/lib/postgresql/data/postgresql.conf file based on cluster size and resources as follows:
    Small to mid-sized clusters: Consider the following settings as starting points. If resources are limited, consider reducing the buffer sizes and checkpoint segments further. Ongoing tuning may be required based on each host's resource utilization. For example, if the Cloudera Manager server is running on the same host as other roles, the following values may be acceptable:
    • max_connection: In general, allow each database on a host a maximum of 100 connections and then add 50 extra connections. You may have to increase the system resources available to PostgreSQL.
    • shared_buffers: 256 MB
    • wal_buffers: 8 MB
    • checkpoint_segments: 16. Replace configuration parameter checkpoint_segments with min_wal_size and max_wal_size.
      If you previously adjusted checkpoint_segments, the following formula will give you an approximately equivalent setting:
      max_wal_size = (3 * checkpoint_segments) * 16MB
    • checkpoint_completion_target: 0.9
    Large clusters: Can contain up to 1000 hosts. Consider the following settings as starting points:
    • max_connection: for large clusters, allow each database on a host a maximum of 100 connections and then add 50 extra connections. You may have to increase the system resources that is available to PostgreSQL.
    • shared_buffers: 1024 MB. This requires that the operating system can allocate sufficient shared memory.
    • wal_buffers: 16 MB. This value is derived from the shared_buffers value. Setting wal_buffers to be approximately 3% of shared_buffers, up to a maximum of approximately 16 MB is sufficient in most cases.
    • checkpoint_segments: 128. The PostgreSQL Tuning Guide recommends values between 32 and 256 for write-intensive systems, such as this one. Replace configuration parameter checkpoint_segments with min_wal_size and max_wal_size.
      If you previously adjusted checkpoint_segments, the following formula will give you an approximately equivalent setting:
      max_wal_size = (3 * checkpoint_segments) * 16MB
    • checkpoint_completion_target: 0.9
  5. Configure the PostgreSQL server to start when the system boots.
    OS Command
    RHEL 7-compatible, SLES, and Ubuntu 
    sudo systemctl start postgresql
sudo systemctl enable postgresql
  6. Restart the PostgreSQL database.
    OS Command
    RHEL 7-compatible, SLES, and Ubuntu 
    sudo systemctl restart postgresql