Single-node Tamr deployments use the instance of Postgres that is installed as part of the Tamr software package. See Install Postgres and Create the Database. Alternatively, you can configure Tamr to use an external instance of Postgres.

You can configure the following Postgres configuration variables:

Configuration Variable	Description
TAMR_PERSISTENCE_DB_URL	The URL of the database that you can use with the JDBC driver. In the URL, you can optionally specify `ssl=true`. This is useful if you are using an external instance of Postgres. For example, you can use: `jdbc:postgresql://<host>:<port>/<database>?ssl=true`.
TAMR_PERSISTENCE_DB_USER	The user for the Postgres instance.
TAMR_PERSISTENCE_DB_PASS	The encrypted password for the Postgres instance.

Changing the Default Postgres Username and Password

To change the default username and password:

Set a plain-text value for the configuration variable TAMR_PERSISTENCE_DB_USER using the admin tool. See Creating or Updating a Configuration Variable.
Confirm that the current Java is set to Tamr's bundled OpenJDK package, and that the environment variable JAVA_HOME is set.

which java
<tamr-home-directory>/openjdk-8u222/bin/java
echo $JAVA_HOME
<tamr-home-directory>/openjdk-8u222

If those aren't set, run the following commands (assuming bash shell):

export JAVA_HOME=<tamr-home-directory>/openjdk-8u222
export PATH=$JAVA_HOME/bin:$PATH

Encrypt the database user's password using the utility encrypt.sh as follows:

cd <tamr-home-directory>/tamr
./encrypt.sh -AES256
Please enter a password to encrypt:

Set the configuration variable TAMR_PERSISTENCE_DB_PASS to the encrypted output generated in Step 3 using the administration utility. See Setting configuration variables.
Restart Tamr and its dependencies. See Restarting.