PostgreSQL-incompatible SQL in activity_delete()

Under PostgreSQL, here is an error:

DELETE m, at, aa, a FROM activity a LEFT JOIN activity_access aa ON aa.aid = a.aid INNER JOIN activity_targets at ON at.aid = a.aid INNER JOIN activity_messages m ON m.amid = at.amid WHERE a.aid IN (48050,48051,48053,48055)

SQL guidelines for Drupal can be read here:
http://drupal.org/node/555514

MySQLism and PostgreSQLism: avoid deleting data in several tables in one query:
http://drupal.org/node/555648

It seems that this delete query should be split in several queries.