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.

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Regards,

Deepak
Oracle DBA