Parallelizing Table Functions
Moving functions into the paradigm of SELECT statements allows them to take advantage of another powerful facet of Oracle—parallel query processing.
Oracle has long provided parallelism as a way to conquer large queries by splitting processing among multiple Parallel Query (PQ) servers, using each to calculate a portion of the results, then assembling a final result set at the end. Behind the scenes, Oracle decides how to distribute the work across the available PQ servers to get the best results. The DBA can influence Oracle’s decision somewhat by setting degrees of parallelism for tables or implementing specific partitioning schemes, but, in the end, the database decides how best to execute the query.
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