title: Upgrade Postgres Extension / Install Specific Version
body: <p>1) How do you upgrade a postgres extension?<br>
  2) How do you install a specific extension version?</p>
  
  <p>In production the version of hstore is out of date.</p>
  
  <pre><code>=&gt; select * from pg_available_extensions where name ='hstore';
    name  | default_version | installed_version |                     comment
  --------+-----------------+-------------------+--------------------------------------------------
   hstore | 1.3             | 1.1               | data type for storing sets of (key, value) pairs
  </code></pre>
  
  <p>All the other environments hstore is already at 1.3 so I don't have a way to test if <code>create extension hstore;</code> is all I need.</p>
  
  <p>I'd like to test the upgrade first and ran Postgres 9.4.4 through Docker</p>
  
  <pre><code>docker run --name some-postgres -e POSTGRES_PASSWORD=mysecretpassword -d postgres:9.4.4
  
  docker run -it --rm --link some-postgres:postgres postgres:9.4.4 psql -h postgres -U postgres
  </code></pre>
  
  <p>but hstore 1.3 was the default version</p>
  
  <pre><code>  name  | default_version | installed_version |                     comment
  --------+-----------------+-------------------+--------------------------------------------------
   hstore | 1.3             | 1.3               | data type for storing sets of (key, value) pairs
  </code></pre>