What Is Oracle Parallel Server?

Oracle Parallel Server is a robust computing environment that harnesses the processing power of multiple, interconnected computers. Oracle Parallel Server software and a collection of hardware known as a cluster, unites the processing power of each component to become a single computing environment. A cluster generally comprises two or more computers. In Oracle Parallel Server environments, all nodes concurrently execute transactions against the same database. Oracle Parallel Server coordinates each node's access to the shared data to provide consistency and integrity. Harnessing the power of multiple computers has many advantages. If you divide a large task into sub-tasks and distribute the sub-tasks among multiple nodes, you can complete the task faster than if only one node did the work. This type of parallel processing is clearly more efficient than sequential processing. In addition, this also provides increased performance to process larger workloads and accommodate growing user populations. If you establish high node-to-data affinity with accurate partitioning, you can effectively scale your applications to meet increasing data processing demands. As you add resources, Oracle Parallel Server can exploit them and extend their processing powers beyond the limits of the individual components. You can use Oracle Parallel Server for many system types. Furthermore, Oracle Parallel Server successfully manages increasing numbers of online transaction processing systems as well as hybrid systems that combine the characteristics of both read-only and read/write applications. Oracle Parallel Server also serves as an important component of robust High Availability solutions. A properly configured Oracle Parallel Server environment can tolerate failures with minimal or no downtime.

Some of the most important benefits beyond the advantages of parallel processing are described in the following paragraphs. These benefits include improved throughput and scalability over single-instance systems and improved response time. An Oracle Parallel Server also provides an ideal High Availability solution by resolving node failure in a clustered environment. Oracle Parallel Server environments are functionally transparent when compared to single-instance environments because they are functionally identical to single-instance environments.

If the necessary parallel server processes are not available for parallel execution, a SQL statement is queued when the parallel degree policy is set to automatic. After the necessary resources become available, the SQL statement is dequeued and allowed to execute. The parallel statement queue operates as a (FIFO) first-in, first-out queue by default. If the query in front of the queue cannot be scheduled, none of the queries in the queue can be scheduled even if resources are available in the system to ensure that the query at the head of the queue has adequate resources. However, if you configure and set up a resource plan, then you can control the order in which parallel statements are dequeued and the number of parallel servers used by each workload or consumer group.