Barnet Wagman wrote:
> 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.
> 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
concurrently.
-suresh
