9.1.20.3 Exadata Smart Scan Offload Enhancements for In-Memory Aggregation (IMA)

Oracle Exadata Storage Server software supports offloading many SQL operators for predicate evaluation. The In-Memory Aggregation feature attempts to perform a "vector transform" optimization which takes a star join SQL query with certain aggregation operators (for example, SUM, MIN, MAX, and COUNT) and rewrites it for more efficient processing. A vector transformation query is similar to a query that uses bloom filter for joins, but is more efficient. When a vector transformed query is used with Oracle Exadata Storage Server release 12.1.2.1.0, the performance of joins in the query is enhanced by the ability to offload filtration for rows used for aggregation. You will see “KEY VECTOR USE” in the query plan when this optimization kicks in.

In Oracle Exadata Storage Server software release 12.2.1.1.0, vector transformed queries benefit from more efficient processing due to the application of group-by columns (key vectors) to the Exadata Storage Index.

Additionally, vector transformed queries that scan data in in-memory columnar format on the storage server can offload processing of aggregation work. These optimizations are automatic and do not depend on user settings.

Minimum software required: Oracle Database 12c release 2 (12.2.0.1.0) and Oracle Exadata Storage Server software release 12.2.1.1.0