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of the database at the end of a specific transaction . The ID of that transaction is used as the name of the file. A recording file, with the same transaction ID in its name, contains database operations that have been recorded after that transaction . Recorded operations can be replayed

the content of a database require active transactions . Transactions are managed by an EntityTransaction ... ) must be performed within an active transaction . The EntityTransaction interface represents and manages database transactions . Every EntityManager holds a single attached EntityTransaction instance

is locked separately. Optimistic locking is applied on transaction commit. Any database object ... by another transaction . When using ObjectDB, optimistic locking is enabled by default and fully ... must be revealed earlier (before transaction commit) pessimistic locking can be used. When using

connection. Every operation on a database requires a PersistenceManager instance. The Transaction interface represents a transaction on a database. Every operation that modifies the content of the database requires an active transaction . The focus of this chapter is on setting up a runtime

. When a transient object becomes persistent during an active transaction , its content is automatically stored in the database when the transaction is committed (unless it is being deleted before commit). An attempt to call makePersistent( ... ) when there is no active transaction throws an exception

// Create or open a database and begin a transaction : 12 PersistenceManager pm = 13 Utilities ... .hasNext()) 34 System.out.println(itr.next()); 35 36 // Close the transaction and the database: 37 pm ... the content of the database, a transaction is begun (line 14), because in JDO, operations that affect

JDO Interface Transaction The JDO Transaction interface provides for initiation and completion of transactions under user control. It is a sub-interface of the PersistenceManager that deals with options and transaction demarcation. Transaction options include whether optimistic concurrency control

an active transaction for every open database file. All editing operations (including loading classes ... with the active transaction . The "File | Save" menu command (and the equivalent toolbar button) commits the transaction which applies all the changes to the database. The "File | Discard Changes" menu

JDO Method in javax.jdo. Transaction void setIsolationLevel (   String level ) Set the value for transaction isolation level for this transaction . Transaction isolation levels ... serializable Parameters: level - the transaction isolation level See Also: getIsolationLevel () Constants.TX

JDO Method in javax.jdo. Transaction void begin () Begin a transaction . The type of transaction is determined by the setting of the Optimistic flag. Throws: JDOUserException - if transactions are managed by a container in the managed environment, or if the transaction is already active. See Also: setOptimistic getOptimistic Since: JDO 1.0