DBMS | Concurrency: In this tutorial, we will learn about the concurrency in DBMS, advantages of concurrency, and problems due to concurrency.
The read-only concurrency strategy in 6.x used Exclusive concurrency. This guaranteed exclusive access to the bean, but not to the generated Set for the 1-N relationship. It was possible for two clients to get access to the same Set. In such a case, when some method was called on the...
How different types of UPs have to be implemented is described in Frank and Zahle (1998). Some non-heterogeneous versions of these tools have been implemented in e.g. DB2 and Oracle DBMS software. UPs have the following properties, which are important from a performance and an atomicity ...
WebLogic Server was throwing an OptimisticConcurrencyException when order-database-operations was set to true, and if an entity bean was removed and created with the same Primary Key in the same transaction. Now, WebLogic Server does not throw the OptimisticConcurrencyException under these conditions...
A compliance warning has been added indicating that corruption of a Blob Clob may occur if a bean is using optimistic concurrency, has any fields that are mapped to Blob/Clob DBMS columns, and no timestamp or version column has been specified. This warning also recommends the addition of a ...
Column version numbers were not updating correctly with Optimistic concurrency enabled, because blind writes were not checked . The code was changed so that blind writes are checked with Optimistic concurrency. 7.0 SP3 8.1 SP2 CR102481 In some bean-managed stateful session beans, an IllegalStat...
A java.sql.BatchUpdateException: ORA-01006 or java.lang.ArrayIndexOutOfBoundsException is thrown when enable-batch-operations is set to true for an EJB that uses Optimistic Concurrency and a batch of queries arrive such that a parameter is null in the predicated clause of one query and not ...