在PostgreSQL客户端psql中，可以使用\df查看数据库搜索路径下的所有函数：
**postgres=# \df**
List of functions
Schema | Name | Result data type |
Argument data types
| Type
--------+-----------------------+--------------------+--------------------------
---------------------------------------------------------------------------------
-----------------------------------------------------------------------------------
-------------------------------------------------------------------------+---------
public | __arima_adjust|double precision[]|distid integer,
curr_tvals double precision[], prev_tvals double precision[], p integ
er
| normal
public | __arima_diff因为PostgreSQL中的函数有四种分类：aggregates/normal/trigger/window functions，所以psql中提供了附加参数，分别用来显示对应的函数：\dfa、\dfn、dft、dfw：
postgres=# \dft
List of functions
Schema | Name | Result data type | Argument data types | Type
--------+--------------------+------------------+---------------------+---------
public | checkauthtrigger | trigger | | trigger
public | postgis_cache_bbox | trigger | | trigger
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