Transaction Isolation Level

bapajju · Post by **bapajju** » Tue Dec 02, 2003 4:23 am

While using OCI stage I could find a tab for Transaction Isolation Level.There are three options in this viz. Read Committed, Serializable and Read Only. Can somebody explain what is the difference between these three options and in what exact situation these are useful.

Thanks
Bapajju

WoMaWil · Post by **WoMaWil** » Tue Dec 02, 2003 6:15 am

There is a lot of documention in DataBase theory about it, where you can find a whole bunch of information. It is important to know for operational systems. In a DWH environment it can be used, but doesn't fit so much the needs of mass Data processing.

Wolfgang

chulett · Post by **chulett** » Tue Dec 02, 2003 6:57 am

Click on the 'Help' button in the OCI stage and find that field. The three options are explained fairly well there. From memory, they mostly center around whether changes to the base data you are querying will be seen by your (long running) query or not.

IIRC, they also have an impact on whether 'locks for update' are taken. When I'm sourcing from Oracle for 'delivery' elsewhere, I generally set it to 'Read Only'.