pull and push postgresql extensions错误消息

Question

当我将数据库从heroku拉到localhost时，我收到此消息：

▸    WARNING: Extensions in newly created target database differ from existing source database.
▸    Target extensions:
▸    
▸    Source extensions:
▸    extname
▸    ----------
▸    plpgsql
▸    unaccent
▸    (2 rows)

在localhost上我得到了这个：

select * from pg_available_extensions;
        name        | default_version | installed_version |                               comment                                
--------------------+-----------------+-------------------+----------------------------------------------------------------------
 unaccent           | 1.1             |                   | text search dictionary that removes accents

(52 rows) #cut for brievity

但是：

select * from pg_extension;
 extname | extowner | extnamespace | extrelocatable | extversion | extconfig | extcondition 
---------+----------+--------------+----------------+------------+-----------+--------------
 plpgsql |       10 |           11 | f              | 1.0        |           | 
(1 row)

在heroku上：

DATABASE=> select * from pg_extension;
 extname  | extowner | extnamespace | extrelocatable | extversion | extconfig | extcondition 
----------+----------+--------------+----------------+------------+-----------+--------------
 plpgsql  |       10 |           11 | f              | 1.0        |           | 
 unaccent |       10 |      5147991 | t              | 1.1        |           | 
(2 rows)

所以我想问题是如何在本地激活unaccent。另一个问题是：为什么我会在plpgsql上收到此消息？