You can set customized isolation levels by using the SET TRANSACTION ISOLATION LEVE statement. However, combinations of isolation levels below are not supported. If they are used, a system error message is shown up and an isolation level closest to the one specified is chosen.
The following are unsupported isolation levels. If table schema is changed while data is selected, unrepeatable read occurs; therefore, the combinations below are not supported.
Neither are isolation levels below supported because updating a row by a transaction is not allowed while table schema is changed by other transaction.