[rabbitmq-discuss] max amount of persisted data

[tsuraan]

> Mnesia is only used for storing routing and configuration data. Messages
> are persisted to a disk_log in a snapshot+delta format.

Ok, makes sense.

> Yes, but with some important caveats:
>
> - All persisted data is currently also held in memory and hence bounded
> by that.
...
> The plans we have for disk-based queues remove these limitations.

Would replacing the queue currently used for unacked_message_q in
rabbit_channel.erl with a queue that overflows to a tempfile be
sufficient to resolve this?  I have a (minimally tested) queue that
does that.  I guess the calls to queue:to_list would have to be
replaced with something fold-based or it would defeat the purpose of
the whole thing, but is that basically what needs to be done?