# TL;DR

After upgrade to Ubuntu 17.04:

```bash
sudo pg_dropcluster 9.6 main --stop
sudo pg_upgradecluster 9.5 main
sudo pg_dropcluster 9.5 main
```

# Upgrade PostgreSQL


During Ubuntu updgrade to 17.04 you receive this message "Configuring postgresql-common":

```
Obsolete major version 9.5

The PostgreSQL version 9.5 is obsolete, but the server or client packages are still installed.
Please install the latest packages (postgresql-9.6 and postgresql-client-9.6) and
upgrade the existing clusters with pg_upgradecluster (see manpage).

Please be aware that the installation of postgresql-9.6 will automatically create a default cluster 9.6/main.
If you want to upgrade the 9.5/main cluster, you need to remove the already existing 9.6 cluster
(pg_dropcluster --stop 9.6 main, see manpage for details).

The old server and client packages are no longer supported.
After the existing clusters are upgraded, the postgresql-9.5 and postgresql-client-9.5 packages should be removed.

Please see /usr/share/doc/postgresql-common/README.Debian.gz for details.
```

Use `dpkg -l | grep postgresql` to check which versions of postgres are installed:

```bash
ii  postgresql                 9.6+179                all     object-relational SQL database (supported version)
ii  postgresql-9.5             9.5.6-0ubuntu0.16.10   amd64   object-relational SQL database, version 9.5 server
ii  postgresql-9.6             9.6.2-1                amd64   object-relational SQL database, version 9.6 server
ii  postgresql-client          9.6+179                all     front-end programs for PostgreSQL (supported version)
ii  postgresql-client-9.5      9.5.6-0ubuntu0.16.10   amd64   front-end programs for PostgreSQL 9.5
ii  postgresql-client-9.6      9.6.2-1                amd64   front-end programs for PostgreSQL 9.6
ii  postgresql-client-common   179                    all     manager for multiple PostgreSQL client versions
ii  postgresql-common          179                    all     PostgreSQL database-cluster manager
ii  postgresql-contrib-9.5     9.5.6-0ubuntu0.16.10   amd64   additional facilities for PostgreSQL
ii  postgresql-contrib-9.6     9.6.2-1                amd64   additional facilities for PostgreSQL
```

Run `pg_lsclusters`, your 9.5 and 9.6 main clusters should be "online".

```bash
Ver Cluster Port Status Owner    Data directory               Log file
9.5 main    5433 online postgres /var/lib/postgresql/9.5/main /var/log/postgresql/postgresql-9.5-main.log
9.6 main    5432 online postgres /var/lib/postgresql/9.6/main /var/log/postgresql/postgresql-9.6-main.log
```

There already is a cluster "main" for 9.6 (since this is created by default on package installation).
This is done so that a fresh installation works out of the box without the need to create a cluster first,
but of course it clashes when you try to upgrade 9.5/main when 9.6/main also exists.
The recommended procedure is to remove the 9.6 cluster with `pg_dropcluster` and then upgrade with `pg_upgradecluster`.

Stop the 9.6 cluster and drop it.

```bash
sudo pg_dropcluster 9.6 main --stop
```

Upgrade the 9.5 cluster to the latest version.

```bash
sudo pg_upgradecluster 9.5 main
```

Your 9.5 cluster should now be "down" and you can verifity running `pg_lsclusters`

```bash
Ver Cluster Port Status Owner    Data directory               Log file
9.5 main    5433 down   postgres /var/lib/postgresql/9.5/main /var/log/postgresql/postgresql-9.5-main.log
9.6 main    5432 online postgres /var/lib/postgresql/9.6/main /var/log/postgresql/postgresql-9.6-main.log
```

Check that the upgraded cluster works, then remove the 9.5 cluster.

```bash
sudo pg_dropcluster 9.5 main
```

After all your data check you can remove your old packages.

```bash
sudo apt-get purge postgresql-9.5 postgresql-client-9.5 postgresql-contrib-9.5
```

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