diffs on postgres data

[Darren Cook <darrenj@example.com>]

Is there anything like cvs or diff for a postgres (or any SQL) database?

E.g. A table with 1000 records. Each week 5 records deleted, 10 get
changed, and 100 new records get added. I want to be able to checkout a
version of the database as it was at the beginning of any week in the
past, but the further it is in the past the less often I'll need to do
this. The table will always have an id column which is unique.

Darren