For those who aren’t familiar with hstore, it’s a key/value storage type that is packaged as an extension or contrib in PostgreSQL 8.2+. In PostgreSQL 9.0 it got a little extra loving in several ways one of which was the introduction of the hstore(record) casting function that converts a record to an hstore. In this article, I’ll demonstrate how you can use this new casting function to do very sleek mail merges right in the database. The only caveat is that it seems to only correctly name the keys if it is fed a real table or view. Derived queries such as aggregates etc get keys named f1, f2, etc.
If you are on PostgreSQL 9.1 or above installing — hstore is just a CREATE EXTENSION hstore; sql command away. If you are on a lower version of PostgreSQL, you can usually find the hstore.sql in share/contribs.Mas:

http://www.postgresonline.com/journal/archives/238-Mail-Merging-using-Hstore.html