title: How to use pg_trgm after postgresql installation from source
body: <p>After succesfully installing postgresql 9.2.2 from source (on OpenSUSE 11.4, which does not have this version in the repositories),  I am trying to restore a database that makes use of the pg_trgm extension.  This results in errors because pg_trgm is not found.</p>
  
  <p>From this StackOverflow question: <a href="https://stackoverflow.com/questions/2254999/similarity-function-in-postgres-with-pg-trgm">Similarity function in Postgres with pg_trgm</a>,  I gather that pg_trgm should be in /usr/share/postgresql//contrib,  but there is no contrib folder anywhere in my /usr tree.</p>
  
  <p>Also,  I cannot seem to find a clear explanation of how the postgres extension mechanism works,  or how to manually install an extension.</p>
  
  <p>There is a contrib folder in the postgresql source tree,  but I am not sure how to use this.  Should I manually copy this somewhere to /usr tree? Can anyone point me to (or give) an explanation of how to install an extension like pg_trgm in postgresql?</p>