Isolation suitable for ETL

The best isolation level for ETL is DIRTY READ, Cauz it wont set any locks on anything , and wont consider lock exists on any anything , as we have a great chance to ETL DATA from a static data base, As a result, It will cost the least and execute in the fastest way.

In informix, the clause is SET ISOLATION TO DIRTY READ.

the following is the isolation performance in ORACLE. 

Read uncommitted is the same as DIRTY READ.

                  Dirty Read     NonRepeatabe Read       Phantom Read 
Read uncommitted  Possible       Possible                Possible
Read committed    not possible   Possible                Possible
Repeatabe read    not possible   not possible            Possible
Seriaizabe        not possible   not possible            not possible