Thanks for the remark. I've seen recently somebody from the "core" team (was it at PgCon Rev Meeting [1] or a blog) mentioning it meaning to revive it?
It also mentions an insert-only technique: "This approach has been adopted before in POSTGRES [21] in 1987 and was called "time-travel". I would be interested what "time-travel" is and if this is still used by Postgres.
Back in the old days, PostgreSQL never deleted any tuples. Rows were deleted by writing the deletion time into a column. As a result, you could go back to old data just by telling PostgreSQL to report rows which where visible at a given time.
Obviously, this approach precluded use of PostgreSQL in many scenarios. For example, you wouldn't want to use it as your web application session store.
