A couple questions/issues:
Re logging: Something I read in the Derby documentation (or perhaps in
the mailing list archive) indicated that logging may be expensive. Is
there any way to disable logging completely?


I think there is no option available in derby to disable  logging . 
Might be good option for Derby to provide in future releases.

Any idea of difficult this might?  I've been thinking about poking around in the src to try to do this.

Re record vs table locking:  "Tuning Derby" indicates that record
level locking can add a lot of overhead and implied that there's a way
to force table locking, but it wasn't clear to me how to do this.


 1) you can acquire a table level lock  using  LOCK TABLE sql statement .
     ex: lock table t1 in exclusive mode
 2) There is also lock escalation mechanism in derby. When locks on
particular table  in a transaction reaches a threshold
values(default:5000). it automatically escalates  the row level  locks
to a table level lock. Lock escalation threshold  value can be changed
by setting derby.locks.escalationThreshold  property.   I would not
recommend reducing the threshold  if the tables are being accessed

Am I correct in my understanding that escalating to table locking speeds things up?  If so, any idea what threshold level might help?  Also, does this locking mechanism come into play with reads, or just with writes.