Removing old keys

[Tom Yu]

Nicolas Williams <Nicolas.Williams at oracle.com> writes:

> While an RPC may be useful by itself, I think it what's needed is a
> policy such that sufficiently old keys are deleted on next key change.
>
> The safest policy, ISTM, is delete kvno-3 or kvno-2 on key change.  It'd
> be nice too to have a way to flag keys as having been "replicated", as
> may be necessary in cluster situations.  (Though clusters also have to
> worry about replay caches, and that's a different topic.)

We have explored some of these possibilities, such as "not valid
before/after" timestamps on each kvno, or "validity" flags on kvnos.
I would consider those alternatives as a longer-term solution in the
evolution of our database abstraction, while the "purge old keys"
capability is something that can be implemented in the short term.