http://pgolub.wordpress.com/2012/06/22/backward-compatibility-never-heard-of-it
If we had stable system views for all database objects (stable as in we
just append to them), then refactoring our system tables wouldn't break
things for our users. Just sayin'.
(and don't tell me about information_schema, which is fairly useless for
anything except tables and columns)
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com