Changes in Oracle Database Advanced Queuing 12c Release 1 (12.1.0.2)

In Oracle Database 12c Release 1 (12.1.0.2), Advanced Queuing introduces JMS Streaming with enqueue and dequeue for sharded queues through AQjmsBytesMessage and AQjmsStreamMessage, for the applications interested in sending and receiving large message data or payload.

In Oracle Database 12c Release 1 (12.1), Advanced Queuing introduces high performing and scalable sharded JMS Queues. A sharded queue is a single logical queue that is divided into multiple, independent, physical queues through system-maintained partitioning. A sharded queue increases enqueue-dequeue throughput, especially across Oracle RAC instances, because ordering between two messages on different queue shards is best effort. Each shard is ordered based on enqueue time within a session. Sharded queues automatically manage table partitions so that enqueuers and dequeuers do not contend among themselves. In addition, sharded queues use an in-memory message cache to optimize performance and reduce the disk and CPU overhead of AQ-JMS enqueues and dequeues. Sharded queues are the preferred JMS queues for queues used across Oracle RAC instances, for queues with high enqueue or dequeue rates, or for queues with many subscribers.

In Oracle Database 12c Release 1 (12.1), the Rules Engine introduces a result cache to improve the performance of many commonly used rules. The result cache will bypass the evaluation phase if an expression with the same attributes has already been evaluated earlier. Not all rule results are cached, such as when rule results are potentially non-deterministic or when not all rules are evaluated or when attributes include non-scalar data types. For Advanced Queues, the cache is most useful when subscriptions and their dequeue sessions are long-lived.