Modifications and Actions on the Remote Buffers 

 

If the content of a buffered table is modified, this modification is applied transactionally to both the table buffer and the database. Consequently, the buffer is notified about a commit/rollback of a transaction. If a commit occurs, the buffered, changed object remains in the buffer; for a rollback, it is marked as invalid.

The following modification statements can be applied to the buffer:

●      Insert statements

●      Update statements specifying the complete primary key

●      Delete statements specifying all keys of the defined key range with equality.

If more than one key range is affected, all according key ranges will be invalidated - in the worst case the whole table. A modification is directly visible to all threads of the cluster node in which the buffer is located – this means that the buffer operates in the “dirty read” isolation level.

When multiple cluster nodes of the AS Java are in operation, the task of synchronizing the remote table buffer instances arises. It is implemented as follows: the changes to bufferable objects that are made on one buffer instance, do not become directly visible in the remote buffers. Instead, the remote buffers are notified at regular intervals by invalidation requests that invalidate the corresponding key ranges, the whole table in the worst case.