actually installed in a given database.
   </P
><P
>    The kinds of SQL objects that can be members of an extension are shown in
    the description of <A
HREF="sql-alterextension.html"
>ALTER EXTENSION</A
>.  Notably, objects
    that are database-cluster-wide, such as databases, roles, and tablespaces,
    cannot be extension members since an extension is only known within one
    database.  (Although an extension script is not prohibited from creating
    such objects, if it does so they will not be tra