RE: database contention and wait, are they the same?

Hi Kam,

There are some waits that are routine (such as those associated with commits), but most non-idle waits reflect some sort of contention.

Just increasing the concurrency may help a little, or it may hurt, depending on the type of waiting. If it is disk contention, then it will probably help a little; if it were latch contention then it would certainly hurt.

Of course, you should really find out what you are waiting for and fix the problem. While increasing the concurrency may help to reduce the overall run time slightly in the immediate term, it will only do so at a considerable cost in increased CPU usage, and you can only play that game for a very short time. What will happen when your business grows and you have to process twice the number of bills? Don't just thinks waits and performance; think scalability, or you are bound to have the same problem come back to haunt you in a few months time.

Regards,
Steve Adams

http://www.ixora.com.au/
http://www.oreilly.com/catalog/orinternals/
http://www.christianity.net.au/


-----Original Message-----
From:	Kam Chan [SMTP:chank_at_powertel.com.au]
Sent:	Tuesday, May 23, 2000 1:58 AM
To:	Multiple recipients of list ORACLE-L
Subject:	database contention and wait, are they the same?

Dear list,

I have a discussion with my fellow DBA about the difference between database
contention and wait, we had a billing process which run in parallel, multiple instances of the billing program was run to process different ranges of account (it is not parallel query in Oracle). We are discussing how to improve performance of the billing process, one possibility is to increase number of instances of billing process from 4 to 8 since the machine (4 CPUs) are not very busy when the billing processes were running. I argue that if there is contention (result in wait) in the database then increase the number of processes will only make it worst. My fellow DBA said
contention and wait are two different things, I disagree about what he said,
the two things are different in nature, however in my opinion a lot of waits
are result of contention, isn't Oracle records contention in wait statistics?? Anyone who can clarify this??

Kam

--
Author: Kam Chan
  INET: chank_at_powertel.com.au

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