Postgres 9.1 : Installing contrib modules on ec2

Having installed PostgreSQL 9.1 on my ec2 instance (Amazon Linux) following these instructions, I wanted to experiment with a few contrib modules. However, this process was not trivial, mainly because the installed postgres distribution did not have the contrib modules by default. Here's what I did :

1. Checking if the modules exist :
• cd /usr/pgsql-9.1/share/extension
• Only plpgsql seems to be there.
2. Extensions don't exist, preparing to install contrib. Check the specific postgres version first :
• sudo su -
• su - postgres
• /usr/pgsql-9.1/bin/psql -p 5432
• postgres=# select version();
                                                      version                                                    
  ---------------------------------------------------------------------------------------------------------------
   PostgreSQL 9.1.9 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-54), 64-bit
  (1 row)
3. Installing contrib :
• sudo yum install postgresql91-contrib
  Error: Package: postgresql91-contrib-9.1.10-1PGDG.rhel5.x86_64 (pgdg91)
  Requires: libossp-uuid.so.15()(64bit)
4. Whoops! Fixing errors and try installing again :
• Downloaded the required rpm file from the following link.
• wget ftp://ftp.pbone.net/mirror/ftp5.gwdg.de/pub/opensuse/repositories/home:/nick_at_seakr:/epel/RedHat_RHEL-5/x86_64/uuid-1.5.1-5.1.x86_64.rpm
• rpm -Uvh libossp-uuid.so.15 (instructions found here)
5. Success! Checking "/usr/pgsql-9.1/share/extension" indeed shows that the modules were installed. What extensions are installed on my current database?
• sudo su -
• su - postgres
• /usr/pgsql-9.1/bin/psql -p 5432
• postgres=# select * from pg_extension;
   extname | extowner | extnamespace | extrelocatable | extversion | extconfig | e
  xtcondition 
  ---------+----------+--------------+----------------+------------+-----------+--
  ------------
   plpgsql |       10 |           11 | f              | 1.0        |           | 
  (1 row)
• You can use "postgres=# \dx" instead of the select statement if you want. Anyway, it looks like only plpgsql is installed.
6. Let us install some other extensions. These are installed on the current database by default.
• postgres=# create extension pg_trgm;
  CREATE EXTENSION
• postgres=# create extension hstore;

  CREATE EXTENSION
• postgres=# \dx

                                      List of installed extensions

    Name   | Version |   Schema   |                            Description                            

  ---------+---------+------------+-------------------------------------------------------------------

   hstore  | 1.0     | public     | data type for storing sets of (key, value) pairs

   pg_trgm | 1.0     | public     | text similarity measurement and index searching based on trigrams

   plpgsql | 1.0     | pg_catalog | PL/pgSQL procedural language

  (3 rows)

Extra information :

1. How to change the current database :
• postgres=# \connect foobar
  psql (9.1.10, server 9.1.9)

  You are now connected to database "foobar" as user "postgres".
2. How to check the current database :
• postgres=# select current_database();

   current_database 

  ------------------

   postgres

  (1 row)
• But I don't know why you'd need that in this case since you can check the database name in the prompt itself.
3. Here's a list of modules to explore.
4. What I ended up installing :
• foobar=# \dx

                                           List of installed extensions

          Name        | Version |   Schema   |                            Description                            

  --------------------+---------+------------+-------------------------------------------------------------------

   hstore             | 1.0     | public     | data type for storing sets of (key, value) pairs

   pg_stat_statements | 1.0     | public     | track execution statistics of all SQL statements executed

   pg_trgm            | 1.0     | public     | text similarity measurement and index searching based on trigrams

   pgstattuple        | 1.0     | public     | show tuple-level statistics

   plpgsql            | 1.0     | pg_catalog | PL/pgSQL procedural language

   uuid-ossp          | 1.0     | public     | generate universally unique identifiers (UUIDs)

  (6 rows)