PostgreSQL: postgresql.conf and pg_hba.conf explained

Andre_Sostizzo · Jun 4, 2018 2:03:04 PM

It is important to understand the options which PostgreSQL uses to allow connectivity. These principles are valid no matter whether you are using the Qlik Sense Repository Database service to host the database or using a standalone PostgreSQL instance. The two key files which PostgreSQL uses to define who can connect, how they connect, where they can connect from, and how many connections are allowed are:

postgresql.conf
pg_hba.conf

For bundled PostgreSQL instances, the files are located in:

C:\ProgramData\Qlik\Sense\Repository\PostgreSQL\x.x

If you have unbundled PostgreSQL using the Qlik PostgreSQL installer (QPI), the default location is:

C:\Program Files\PostgreSQL\xx\data

For any other standalone PostgreSQL instances, consulting with your database admin to locate the data directory.

Note: Any changes to these files will require a restart of the Qlik Sense Repository Database or PostgreSQL.
Note: Any lines prefixed with a # are commented out and not active.

postgresql.conf

In the postgresql.conf, in a basic Qlik Sense configuration, there are two key configuration options which are important:

listen_addresses
- This configuration defines which NICs PostgreSQL will listen on. For standalone PostgreSQL servers or multi-node Qlik Sense sites, the recommended setting is * (example below). This allows PostgreSQL to bind to any NICs presented to the server. Multiple comma-separated DNS entries may be added as well. (e.g. listen_addresses = 'localhost,QlikServer2.domain.local' ) More advanced configurations are possible here but will not be covered in this guide.
max_connections
- This configuration defines how many connections PostgreSQL will allow. It is best to use a rule of thumb of about 110 connections per node +20. For example, for 4 nodes set to 460. See Installing Qlik Sense in a multi node for more details.

Where these lines are can vary but an expected single node Qlik Sense site would look like this:

listen_addresses = '*'
max_connections = 100

pg_hba.conf

The pg_hba.conf file defines a variety of aspects:

What IP addresses or ranges can connect to PostgreSQL and for what accounts
What method of authentication those IP ranges / accounts can use
For more details on configuration options for IP listeners, such as samenet, see https://www.postgresql.org/docs/9.6/auth-pg-hba-conf.html

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::/0                 md5
# Allow replication connections from localhost, by a user with the
# replication privilege.
#host    replication     postgres        127.0.0.1/32            md5
#host    replication     postgres        ::1/128                 md5
host	all	            all	            0.0.0.0/0	            md5

In this example pg_hba.conf file there two active lines. The first line specifies that all users can connect to all databases from the local loopback IP using MD5 authentication (host all all 127.0.0.1/32 md5). The second line specifies that all users can connect to all databases from any valid IPv4 address using MD5 authenication (host all all 0.0.0.0/0 md5)

Please review our help for references to more sophisticated configurations where specific IP addresses or IP address ranges are covered.

To recap, when ensuring connectivity in a Qlik Sense Shared Persistence environment, especially a multi-node site, the core configurations which are needed are:

PostgreSQL configured to listen to an external IP address (listen_address in postgresql.conf)
Sufficient connections available for Qlik Sense (max_connections in postgresql.conf)
Explicit allowing the IP address which is used to connect (pg_hba.conf)