Question

给定复合类型的typname，如何以递归方式找到所有组件类型的类型oids？

示例：

CREATE TYPE t_station AS (x INT, y INT, label VARCHAR); CREATE TYPE t_address AS (city VARCHAR, street VARCHAR, no INT, stations t_station[]); CREATE TYPE t_employee AS (name VARCHAR, age INT, coins INT[], notes VARCHAR, address t_address);

我可以获得oids成员的t_employee类型：

SELECT t.typname, t.oid, a.attname, a.atttypid FROM pg_attribute a INNER JOIN pg_type t ON a.attrelid = t.typrelid AND t.typname = 't_employee'

但是我需要对此进行说明，我想可以使用WITH RECURSIVE：
来完成
WITH RECURSIVE allattrs(typname, oid, attname, atttypid) AS ( select t.typname, t.oid, a.attname, a.atttypid from pg_attribute a inner join pg_type t on a.attrelid = t.typrelid and t.typname = 't_employee' union all select z.* from (select t.typname, t.oid, a.attname, a.atttypid from pg_attribute a inner join pg_type t on a.attrelid = t.typrelid) z, allattrs y where y.atttypid = z.oid ) SELECT * FROM allattrs limit 100 ;

但是找不到t_station复合类型的内部数组。

Answer 1

数组类型会破坏您所遵循的简单链。如果是数组类型，则必须解析pg_type.typelem以获取基类型。

WITH RECURSIVE cte(typname, type_oid, attname, atttypid, typelem) AS (
   SELECT t.typname, t.oid, a.attname, a.atttypid, t.typelem
   FROM   pg_type t
   LEFT   JOIN pg_attribute a ON  a.attrelid = t.typrelid
                              AND a.attnum > 0
                              AND NOT a.attisdropped
   WHERE  t.typrelid = 't_employee'::regclass

   UNION ALL
   SELECT t.typname, t.oid
         ,COALESCE(a.attname, t.typelem::regtype::text)
         ,COALESCE(a.atttypid, t.typelem), t.typelem
   FROM   cte c
   JOIN   pg_type t ON t.oid = c.atttypid AND (t.typtype = 'c' OR t.typelem > 0)
   LEFT   JOIN pg_attribute a ON  a.attrelid = t.typrelid
                              AND a.attnum > 0
                              AND NOT a.attisdropped
   )
SELECT typname, type_oid, attname, atttypid
FROM   cte
WHERE  typelem = 0  -- filter out rows for array types

如果要在结果中包含数组类型的额外行，请删除最终的WHERE条件..

此JOIN条件仅遵循复合类型或数组：

AND (t.typtype = 'c' OR t.typelem > 0)

我还添加了排除系统列和死列的条件：

AND a.attnum > 0
AND NOT a.attisdropped

Details about catalog tables in the manual.

使用WITH RECURSIVE查找所有复合类型组件类型

1 个答案: