Re: Asynchronous Commit in Oracle Database 10g R2

orauser wrote:
> Dear Gurus,
>
> Just read this article about "Asynchronous Commit in Oracle Database
> 10g R2" on
> http://itzkdb.blogspot.com/2005/08/asynchronous-commit-in-oracle-database.html
> .
>
> Can some of you comment whether all the information/warnings given in
> this article are true?
>
> Cheers,
> orauser

>From the Oracle 10gR2 documentation for COMMIT, found at
http://download-east.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_4010.htm :

"WRITE Clause

Use this clause to specify the priority with which the redo information generated by the commit operation is written to the redo log. This clause can improve performance by reducing latency, thus eliminating the wait for an I/O to the redo log. Use this clause to improve response time in environments with stringent response time requirements where the following conditions apply:

• The volume of update transactions is large, requiring that the redo log be written to disk frequently.
• The application can tolerate the loss of an asynchronously committed transaction.
• The latency contributed by waiting for the redo log write to occur contributes significantly to overall response time."

Note the second bulleted comment, regarding the toleration of transaction loss due to asynchronous writes. This is not for everybody, nor is it for everyday use in 99.9% or better of production systems currently running. Committing a transaction in a manner which may or may not get it to the redo logs is questionable and deserves CAREFUL thought and consideration before implementation. This is very much like operating an enterprise accepting only credit card sales and doing so in a fashion whereby the credit card company may or may not have a record of the transaction to keep your sales brisk, making reimbursement to you impossible for some sales. Could YOU run a business in that fashion and tolerate lost revenue? I would take great caution with that scenario, and likely not accept it. So would I take great care in considering asynchronous commits. The end result does not appear to be desirable in my viewpoint.

To answer your question, yes, the caveats presented are real and verifiable. Why do you find it so difficult to believe the truth? Or, do you choose to believe the truth when it matches your concept, and question it when it flies in the face of your limited knowledge? Read through the documentation at tahiti.oracle.com, carefully. There is much you need to learn.

David Fitzjarrell Received on Sat Aug 27 2005 - 16:30:26 CDT