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From Barnet Wagman <b.wag...@comcast.net>
Subject Re: Suggestions for improving performance?
Date Wed, 15 Dec 2004 02:12:15 GMT
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
>concurrently.
>
>  
>
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.

Thanks


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