RE: ISOLATION LEVEL

If there is no ddl to run, then it appears to me that set transaction read only is the command Oracle designed for this situation. Or, as Niall stated, use an anonymous block.  

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of DBA Deepak Sent: Tuesday, July 10, 2007 4:09 AM
To: oracle-l
Subject: ISOLATION LEVEL  

Hi All,  

Have a doubt on transaction isolation.  

My requirement is to query several tables several times inside a piece of code. The data needs to be consistent across multiple queries. The underlying tables are subjected to change during the execution of the piece of code.  

I have two options to be used inside my piece of code to achieve consistent/repeatable reads.  

1> to use SET TRANSACTION READ ONLY;

2> to use ALTER SESSION SET ISOLATION_LEVEL=SERIALIZABLE;  

My question is which option is preferable and why? Is there any performance issues with one of these in the above mentioned scenarios?  

Need your valuable feedback.

-- 
Regards,

Deepak
Oracle DBA 


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