If a connection does not specify its isolation level, it inherits
the default isolation level for the Derby system.
The default value is CS.
When set to CS, the connection inherits the TRANSACTION_READ_COMMITTED
isolation level. When set to RR, the connection inherits
the TRANSACTION_SERIALIZABLE isolation level, when set to RS,
the connection inherits the TRANSACTION_REPEATABLE_READ isolation level, and
when set to UR, the connection inherits the TRANSACTION_READ_UNCOMMITTED
isolation level.
To override the inherited default, use the methods of java.sql.Connection.
In addition, a connection can change the isolation level of the transaction
within an SQL statement. For more information, see "SET ISOLATION statement"
in the Derby Reference Manual. You can
use the WITH clause to change the isolation level for the current statement
only, not the transaction. For information about the WITH clause, see
"SELECT statement" in the Derby Reference Manual.
In all cases except when you change the isolation level using the WITH
clause, changing the isolation level commits the current transaction. In most
cases, the current transaction is committed even if you set the isolation level
in a way that does not change it (that is, if you set it to its current value).
See Isolation levels and concurrency for details.
Note: For information about how to choose a particular isolation level, see
"Shielding users from Derby class-loading events" in
Tuning Derby and
Multi-thread programming tips.
