The module was installed into the schema extensions
. I guess that that schema is not in your search path and therefor the function is not found. Try
select extensions.similarity('hello','hell');
If you don't want to fully-qualify the function names you can simply add that schema to your search_path:
alter user your_pg_user set search_path = public,extensions;
If that still gives an error your Postgres user might not have the necessary privileges to call the functions. In that case log in as the superuser (typically postgres
) and grant the priviliges:
grant all on schema extensions to your_pg_user;