Umm. No, you don't. The CREATE EXTENSION does this. With 9.1,
there's a new structure. To check, run psql:
psql -U postgres your_database
at the SQL prompt (database=#) enter:
\dx<Enter>
you should see something like this:
List of installed extensions
Name | Version | Schema | Description
-----------+---------+------------+------------------------------------------------------------
plpgsql | 1.0 | pg_catalog | PL/pgSQL procedural language
tablefunc | 1.0 | public | functions that manipulate whole
tables, including crosstab
See the Version number? It corresponds to the tablefunc--1.0.sql
version number.
Unlike the contrib stored procedures, extensions aren't inherited from
template1 (don't ask me why, they just aren't).