consider a UUID for pool id

[emergent-reasons]

A pool uuid would have these benefits:

• remain internal as the num is now so it should not make anything harder for users
• remove ambiguity when investigation a problem in the logs

Any downsides? It does not happen often and uuid creation is already fast/efficient.

[cculianu]

I can see this as only a win. Definitely makes it easier to track log files ... That corresponds to the "sessionID" in the client, correct?

[emergent-reasons]

Not the sessionID. The sessionID is for a specific connection and is I think is shared around publicly but the pool number is never mentioned in normal messaging. Maybe not anywhere.

Moreover, I believe the sessionID is actually redundant - I think we are going to factor it out at some point.