Where does your requirement/code come from. Is your code not a logical transaction? If so why do you need to see wrong/old data at later stages. If it is a logical transaction then make it a single transaction and you'll only see consistent data.

 

Something doesn't sound quite right but without seeing either your code or your requirements it's somewhat tricky to tell.
 

 

On 7/10/07, DBA Deepak <oracle.tutorials@gmail.com> wrote:

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