Re: inherited type

On Fri, Apr 01, 2005 at 12:42:19PM +0200, Miguel Angel Tribaldos Hervas wrote:
>
> I am working with inheritance in postgresql 7.4. If I create a table named A,
> and another named B that inherits from A, if I perform a query such a
> "SELECT * FROM A" (without ONLY clause),
> how can I get the type (identifier from pg_type) of the returned records??

You can look at the tableoid system column to get the oid from
pg_class:

  CREATE TABLE parent (pid integer);
  CREATE TABLE child (cid integer) INHERITS (parent);

  INSERT INTO parent (pid) VALUES (1);
  INSERT INTO child (pid, cid) VALUES (2, 3);

  SELECT tableoid, tableoid::regclass, * FROM parent;
   tableoid | tableoid | pid
  ----------+----------+-----
      39455 | parent   |   1
      39457 | child    |   2
  (2 rows)

If necessary, you could join tableoid against pg_type.typrelid
or pg_class.oid:

  SELECT t.typname, p.*
  FROM parent AS p
  JOIN pg_type AS t ON t.typrelid = p.tableoid;
   typname | pid
  ---------+-----
   parent  |   1
   child   |   2
  (2 rows)

  SELECT c.relname, p.*
  FROM parent AS p
  JOIN pg_class AS c ON c.oid = p.tableoid;
   relname | pid
  ---------+-----
   parent  |   1
   child   |   2
  (2 rows)

--
Michael Fuhr
http://www.fuhr.org/~mfuhr/