Oracle International Corporation

Nirav Vyas

Mohamed Zait

Jiaqi Yan

Dinesh Das

Shasank Kisan Chavan

Rafi Ahmed

Hariharan Lakshmanan

Gary Smith

Techniques are provided for optimizing workload performance by automatically discovering and implementing performance optimizations for in-memory units (IMUs). A system maintains a set of IMUs for processing database operations in a database. The system obtains a database workload information for the database system and filters the database workload information to identify database operations in the database workload information that may benefit from performance optimizations. The system analyzes the database operations to identify a set of performance optimizations and ranks the performance optimizations based on their potential benefit. The system selects a subset of the performance optimizations, based on their ranking, and generates new versions of IMUs that reflect the performance optimizations. The system performs verification tests on the new versions of IMUs and analyzes the tests to determine whether the new versions of IMUs yield expected performance benefits. The system then categorizes the new set of IMUs into a first set of IMUs to be retained and a second set of IMUs to be discarded. The system then makes the first set of IMUs available to the current workload and discards the second set of IMUs.

Optimize workload performance by automatically discovering and implementing in-memory performance features

Techniques are described herein for filtering data from a table during an in-memory scan. Predicates are pushed to in-memory scan to avoid scanning unnecessary columnar units and reduce the overhead of decompressing, row stitching and distributing data during evaluation. Techniques are described herein for generating implied predicates that have conditions on single columns from complex predicates that have multiple conditions on the same column, which can be evaluated during an in-memory scan. Techniques are also described herein to reduce the overhead of a table scan for processing a join query. When redistributing a first table for performing a hash-join, the nodes performing an in-memory scan of the first table may create a filter that tracks unique values from the join key. Data from the second table is only processed and transferred to other nodes in the cluster if the values from the join key pass through the filter.

Techniques for evaluating query predicates during in-memory table scans

Methods, stored instructions, and computer systems are described for selecting an OR-expansion state of a query. A query processor accesses a certain query and a control parameter. The certain query comprises disjunctive predicates, and the control parameter indicates a certain procedure of a plurality of alternative stored procedures for expanding queries comprising disjunctive predicates into semantically equivalent candidate queries comprising combinations of subqueries. Based at least in part on the control parameter, the query processor selects the certain procedure to expand the certain query into one or more certain semantically equivalent candidate queries, each comprising a different combination of two or more subqueries. The query processor causes cost-based evaluation of subject queries, including the certain query and the one or more certain semantically equivalent candidate queries. The query processor then selects a query of the subject queries for execution or for further evaluation or transformation.

Selecting from OR-expansion states of a query

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Karnataka, India

Nirav Vyas