plgpsql - is it possible to declare setof record or table variable?

Question

I have the following - not working - function:

CREATE FUNCTION permission_cache_update(affected_user_list int[])
  RETURNS TABLE(user_id INT4, permission_id INT4)
AS
  $BODY$
  DECLARE
    current_relations SETOF RECORD;
  BEGIN

  WITH
  affected_user AS (
     SELECT unnest(affected_user_list) AS u_id
  ),
  affected_relations AS (
    SELECT user_role.user_id, role_permission.permission_id
      FROM   user_role
      JOIN   role_permission ON user_role.role_id = role_permission.role_id
      JOIN   affected_user ON affected_user.u_id = user_role.user_id
    UNION
    SELECT user_permission.user_id, user_permission.permission_id
      FROM   user_permission
      JOIN   affected_user ON affected_user.u_id = user_permission.user_id
  )
  SELECT affected_relations.user_id, affected_relations.permission_id FROM affected_relations
  INTO current_relations;

  DELETE FROM permission_cache WHERE ARRAY[user_id] <@ affected_user_list;
  INSERT INTO permission_cache (user_id, permission_id) SELECT user_id, permission_id FROM current_relations;

  END
  $BODY$
LANGUAGE plpgsql;

I want to store the current user-permission relations in current_relations as (INT4, INT4). Is it possible to do this with variables without loops and temporary tables?

I'll use something like this later, so I really need it as variables, not as subquery

DELETE FROM permission_cache WHERE ARRAY[user_id] <@ affected_user_list AND NOT IN (SELECT user_id, permission_id FROM current_relations);

INSERT INTO permission_cache (user_id, permission_id) SELECT user_id, permission_id FROM current_relations WHERE NOT EXIST (SELECT user_id, permission_id FROM permission_cache);

I think it is possible with table -> 2d array conversions, but that's complicated, so if it possible with records, it would be better...

Solution:

It was easier to create a loop with 1d array instead of using records or 2d arrays:

CREATE FUNCTION permission_cache_update(
  IN affected_user_list INT4 []
)
  RETURNS VOID
AS
  $BODY$
  DECLARE
    user_index                    INT4;
    current_user_id INT4;
    current_permission_relations  INT4 [];
    deleted_permission_relations  INT4 [];
    inserted_permission_relations INT4 [];
  BEGIN
    FOR user_index IN 1 .. array_upper(affected_user_list, 1) LOOP
      current_user_id := affected_user_list[user_index];

      WITH
          user_permission_summary AS
        (
          SELECT
            role_permission.permission_id
          FROM user_role, role_permission
          WHERE role_permission.role_id = user_role.role_id AND user_role.user_id = current_user_id
          UNION
          SELECT
            user_permission.permission_id
          FROM user_permission
          WHERE user_permission.user_id = current_user_id
        )
      SELECT
        array_agg(permission_id)
      FROM user_permission_summary
      INTO current_permission_relations;

    SELECT
      array_agg(permission_cache.permission_id)
    FROM permission_cache
    WHERE permission_cache.user_id = current_user_id AND ( current_permission_relations IS NULL OR
          NOT (ARRAY [permission_cache.permission_id] <@ current_permission_relations) )
    INTO deleted_permission_relations;

    SELECT
      array_agg(inserted_permission_id)
    FROM unnest(current_permission_relations) AS inserted_permission_id
    WHERE NOT EXISTS(SELECT
                       1
                     FROM permission_cache
                     WHERE permission_cache.user_id = current_user_id AND
                           permission_cache.permission_id = inserted_permission_id)
    INTO inserted_permission_relations;

    DELETE FROM permission_cache
    WHERE permission_cache.user_id = current_user_id AND
          permission_cache.permission_id = ANY (deleted_permission_relations);

    INSERT INTO permission_cache (user_id, permission_id)
      SELECT
        current_user_id,
        inserted_permission_id
      FROM unnest(inserted_permission_relations) AS inserted_permission_id;

    END LOOP;
  END;
  $BODY$
LANGUAGE plpgsql VOLATILE;

off: Pplpgsql is a very poor language with an even poor documentation, I don't like it... Sorry for the code formatting, autoformat in my IDE is not so good... :S

Answer 1

I think this simplified SQL function might do what you are looking for:

CREATE FUNCTION permission_cache_update(affected_user_list int[])
  RETURNS void AS
$func$

DELETE FROM permission_cache p
USING (SELECT unnest($1) AS u_id) a
WHERE  p.user_id = a.u_id;

INSERT INTO permission_cache (user_id, permission_id)
SELECT u.user_id, r.permission_id
FROM   user_role u
JOIN   role_permission r USING (role_id)
JOIN  (SELECT unnest($1) AS u_id) a ON a.u_id = u.user_id
UNION
SELECT p.user_id, p.permission_id
FROM   user_permission p
JOIN  (SELECT unnest($1) AS u_id) a ON a.u_id = p.user_id;

$func$ LANGUAGE sql;

Writable CTE (a.k.a. data-modifying CTE) would simplify this tremendously but were only introduced with Postgres 9.1. Once again, your outdated version is in the way.

Referencing parameters by name was only introduced in Postgres 9.2 for SQL functions (earlier for plpgsql). So I use the positional parameter $1.