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From Suresh Thalamati <tsur...@Source-Zone.org>
Subject Re: Suggestions for improving performance?
Date Tue, 14 Dec 2004 23:41:37 GMT
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


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