Exadata Parallel Operations

Abstract

Exadata doesn’t have a special way of executing parallel operations that is not available on other platforms running 11gR2. However, parallel processing is a key component of Exadata because efficient handling of Data Warehouse workloads was a primary design goal for Exadata. In addition, because Offloading/Smart Scan depends on direct path reads, which are used by parallel query slaves, parallel operations take on a whole new importance. Traditionally, the use of parallel query has required careful control of concurrency in order to maximize the use of available resources without overwhelming the system. Oracle’s previous attempts at throttling parallel operations to allow them to be used in multiuser environments have not been entirely successful. 11gR2 provides some new capabilities for controlling parallel operations. In particular, a queuing mechanism has been introduced that allows the number of concurrent parallel processes to be managed more effectively. This approach appears to be much better suited to allowing a high degree of parallelism without overwhelming the available resources than previous attempts. 11gR2 also introduced the ability for Oracle to automatically calculate a degree of parallelism on a statement-by-statement basis.