hello …. im here to shared again about installation postgresql 😀 this is new version stable 😀
This is a very quick and painless process. If you have not done so already, make your life easier by installing python-software-properties:

WARNING!! If  you have old version, you can delete before installation

$sudo apt-get purge postgresql*
$sudo apt-get update

next :
$sudo apt-get install python-software-properties

Next up is adding the backports repo and updating apt:

$sudo add-apt-repository ppa:pitti/postgresql && sudo apt-get update

UPDATE: In the comments, Jason Froebe points out that if you already have an earlier version of PostgreSQL installed, you can just upgrade it:

$ sudo apt-get upgrade

Finally install postgresql-9.0:

$ sudo apt-get install postgresql-9.0 libpq-dev

The libpq-dev package is for compiling wrappers/clients against libpq.

There you’re done!

Default config directory is: /etc/postgresql/9.0/main
Default data directory is: /var/lib/postgresql/9.0/main

Cheers 😀