+++
date = "2011-11-22"
title = "Upgrade postgresql-8.4 to postgresql-9.1 on debian"
tags = ["Ubuntu", "debian", "dba", "postgres", "postgresql"]
slug = "upgrade-postgresql-8-4-to-postgresql-9-1-on-debian"
+++
Today I upgraded a production PostgreSQL 8.4 database to version 9.1. This was on a Debian server.
~
The first step is to make a full dump of your data. I personally like to store that dump somewhere safe before upgrading. As root:

``` shell
su - postgres
pg_dumpall > dump.sql
exit
cp ~postgres/dump.sql /root/
```

Now you can safely remove the postgresql-8.4 and install postgresql-9.1:

``` shell
aptitude purge postgresql-8.4
aptitude install postgresql-9.1
```

Next check the postgresql configuration in `/etc/postgresql/9.1/main`. If you make any changes, make sure to restart postgres with `/etc/init.d/postgresql restart`.

Postgresql 9.1 is now up and running, let's import our data back into it.

``` shell
su - postgres
psql < dump.sql
```

That's all. You're now fully upgraded to PostgreSQL 9.1.