The database industry is clearly in the midst of massive server consolidation, an economic imperative whereby the old-fashioned one database/one server approach of the client-server days has been rendered obsolete. Today, single servers with 32 and 64 CPU’s and hundreds of gigabytes of RAM can host dozens of large Oracle databases.
While the 2nd age of mainframe computing came about to facilitate easier DBA management, there remain the impressive benefits of having a back of dozens of CPU’s to perform full scans very quickly.
When invoking Oracle parallel query, there are many perils and pitfalls:
* Setting parallelism on at the table or system level influences the optimizer, and sometimes makes full-scan operations appear cheaper than they really are.
* Determining the optimal degree of parallelism is tricky. The real optimal degree of parallelism depends on the physical placement of the data blocks on disk as well as the number of processors on the server (cpu_count).
To relieve these issues with parallel query, in Oracle 11g Release 2, the following new parallel query parameters are included:
* The parallel_degree_policy parameter
* The parallel_min_time_threshold parameter
* The parallel_degree_limit parameter
* The parallel_force_local parameter
Follow the link below to take a closer look at these important enhancements to Oracle parallel query in 11g Release 2.
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Oracle 11gR2 new parallel query management enhancements
