sudo su - <tamr-functional-user>
cd <tamr-home-directory>/tamr
./stop-unify.sh
./stop-dependencies.sh

sudo yum install postgresql12

sudo echo "localhost:5432:*:tamr:<tamr-postgres-user-password>" > .pgpass 
sudo chmod 600 .pgpass

pg_dumpall -w -h localhost -U tamr -l doit > dumpfile

sudo systemctl stop postgresql-9.4

sudo yum install postgresql12-server

sudo /usr/pgsql-12/bin/postgresql-12-setup initdb
sudo systemctl enable postgresql-12
sudo systemctl start postgresql-12

listen_addresses = '*'

port = 5432

sudo systemctl restart postgresql-12

sudo mv dumpfile /var/lib/pgsql 
```
13. Make the `dumpfile` location accessible to the PostgreSQL user.
```shell
sudo chown postgres:postgres /var/lib/pgsql/dumpfile
```
14. Switch to the PostgreSQL user, and use `psql` to restore from the `dumpfile`, as follows. The `psql` command restores the postgres and doit databases present in the `dumpfile`. You run it as the `postgres` user against the `postgres` database because, when the command starts on the upgraded instance, the Tamr functional user and the `doit` database do not yet exist on the instance. They are created during the restore process. 
```shell
sudo u - postgres psql -d postgres -f /var/lib/pgsql/dumpfile
logout
```
15. Start Tamr. Use the following commands, or see [Restarting](doc:restarting).
```shell
sudo su - <tamr-functional-user>
cd <tamr-home-directory>/tamr
./start-dependencies.sh
./start-unify.sh
```
16. Optional. Delete the `dumpfile`.
```shell
sudo rm /var/lib/pgsql/dumpfile
```
17. Optional. Disable and uninstall the PostgreSQL client for the previous version.
```shell
sudo yum remove postgresql94
```

#Upgrading PostgreSQL to Version 12 on Ubuntu

These instructions assume that you are running Tamr version before v2020.012.0 and want to upgrade your PostgreSQL instance to v12. 

- If you are installing Tamr v2020.012.0 or greater for the first time, you must install PostgreSQL v12. See [Installing PostgreSQL](doc:installing-postgres) in this documentation.
- If you are upgrading to Tamr v2020.012.0 or greater, you must upgrade to PostgreSQL v12 using these instructions.

**To upgrade Your Instance of PostgreSQL to Version 12:**

1. Stop Tamr and its dependencies. See [Restarting](doc:restarting).
```shell
cd /home/ubuntu/tamr
./stop-unify.sh
./stop-dependencies.sh
```
2. Confirm that a single PostgreSQL cluster with version 9.4 exists.
```shell
sudo pg_lsclusters
```
3. Install the PostgreSQL client version 12.
```shell
sudo apt install postgresql-12 postgresql-client-12
```
4. List PostgreSQL clusters. 
```shell
sudo pg_lsclusters
``` 
You should see two clusters running, with PostgreSQL versions 9.4 and 12.
5. Drop the PostgreSQL 12 cluster and stop it.
```shell
sudo pg_dropcluster 12 main --stop 
```
6. List PostgreSQL clusters to verify that now the PostgreSQL 9.4 cluster is running.
```shell
sudo pg_lsclusters
```
7. Upgrade the 9.4 cluster to PostgreSQL version 12.
```shell
sudo pg_upgradecluster -v 12 9.4 main
```
8. List PostgreSQL clusters to verify that the PostgreSQL cluster with version 9.4 is present but stopped, and the PostgreSQL cluster with version 12 is running.
```shell
sudo pg_lsclusters
```
9.  Verify that PostgreSQL v12 is installed.
```shell
sudo psql --version
```
10. Restore any previous `pg_hba.conf` and `postgresql.conf` modifications. Compare `/var/lib/pgsql/9.4/data/pg_hba.conf`  and `/var/lib/pgsql/12/data/pg_hba.conf` and restore any non-default location for `PG_DATA`.

11. Open `postgresql.conf` and add an entry to it as follows, to make the Postgres instance listen on all addresses, and not only on the loopback address. Save the file.
```shell
listen_addresses = '*'
```
12. Open the `postgresql.conf` again and confirm that the port for PostgreSQL is specified correctly as 5432.  
By default, PostgreSQL 12 binds the port 5432 after an upgrade when it takes over from PostgreSQL 9.4 or earlier. However, your instance of PostgreSQL 12 may not be configured to use port 5432 after restart. This may happen if the port 5432 is taken by the instance with the previous version of PostgreSQL, such as PostgreSQL 9.4, before that instance is dropped.
```shell
port = 5432
```
13. Verify that Tamr can connect to its database  in this instance of PostgreSQL. The default Tamr database name is `doit`.
```shell
sudo psql -h localhost -U tamr -l doit
```
14. Start Tamr and its dependencies, and then upgrade Tamr to v2020.012.0 or greater. See [Upgrading](doc:upgrading).
```shell
./start-dependencies.sh
./start-unify.sh
```
15. Run the Tamr backup to confirm that you have PostgreSQL 12 installed. For example, run:
```shell 
cd utils
./unify-admin.sh upgrade --zipFile ~/unify-<version>.zip --installDir ~/ --nobackup
```
This command should succeed if everything is working as required. 
**Note:** This command should fail if you are upgrading to a Tamr version before v2020.012, because of a PostgreSQL validation error caused by the PostgreSQL version being higher than required.
16. Confirm that there are no other validation errors and then run the upgrade without validation. See [Upgrading](doc:upgrading) and [Validation](doc:validation).
For example, run:
```shell
./unify-admin.sh upgrade --zipFile ~/unify-<version>.zip --installDir ~/ --nobackup --skipEnvironmentValidation PGValidator
```
17. Optional. Drop the PostgreSQL cluster for the previous version. 
```shell 
sudo pg_dropcluster 9.4 main
```