PostgreSQL的：功能

Question

使用說明：

SELECT * FROM information_schema.routines 

或

SELECT * FROM pg_catalog.pg_proc 

我能得到系統的功能列表。 是否存在獲得描述，甚至更好的分類功能的方法？ Like here或here。

我不相信，有人用手打字:)

謝謝！

Answer 1

在psql外殼，你可以得到類似的信息與

\daS 

                       List of aggregate functions 
    Schema |  Name  |  Result data type  |  Argument data types   |      
------------+----------------+-----------------------------+------------------------------------+---------------------- 
pg_catalog | array_agg  | anyarray     | anyelement       | concatenate aggregate 
pg_catalog | avg   | numeric      | bigint        | the average (arithmet 
pg_catalog | avg   | double precision   | double precision     | the average (arithmet 
.... 

你可以看到什麼psql殼確實通過啓動與-E參數外殼得到這個信息：

********* QUERY ********** 
SELECT n.nspname as "Schema", 
    p.proname AS "Name", 
    pg_catalog.format_type(p.prorettype, NULL) AS "Result data type", 
    CASE WHEN p.pronargs = 0 
    THEN CAST('*' AS pg_catalog.text) 
    ELSE 
    pg_catalog.array_to_string(ARRAY(
     SELECT 
     pg_catalog.format_type(p.proargtypes[s.i], NULL) 
     FROM 
     pg_catalog.generate_series(0, pg_catalog.array_upper(p.proargtypes, 1)) AS s(i) 
    ), ', ') 
    END AS "Argument data types", 
    pg_catalog.obj_description(p.oid, 'pg_proc') as "Description" 
FROM pg_catalog.pg_proc p 
    LEFT JOIN pg_catalog.pg_namespace n ON n.oid = p.pronamespace 
WHERE p.proisagg 
    AND pg_catalog.pg_function_is_visible(p.oid) 
ORDER BY 1, 2, 4; 
**************************