International Business Machines Corporation

Afiya Nusrat

Nattavut Sutyanyong

Robert Neugebauer

Abhinav Goyal

A method, computer system, and a computer program product for transforming a scalar sub-query to join with non-provable singleton output, responsive to receiving a parsed representation of a statement, containing a scalar operation, which is correlated to predetermined types of objects, by analyzing the parsed representation to determine eligibility for transformation of any scalar operations. Responsive to a determination of eligibility, a query engine injects additional processing into the parsed representation to defer checking of a 1 row condition required by statement semantics. The query engine further injects processing to utilize a result of the additional processing to validate a single row is produced for each GROUPING/PARTITION key. The parsed representation is modified to remove the 1 row condition. The query engine decorrelates the parsed representation using a predetermined method absent a requirement for a unique key to be present in a predicate of the scalar operation.

Transforming a scalar subquery

A method for transforming a scalar sub-query to join with non-provable singleton output, responsive to receiving a parsed representation of a statement, containing a scalar operation, which is correlated to predetermined types of objects, by analyzing the parsed representation to determine eligibility for transformation of any scalar operations. Responsive to a determination of eligibility, a query engine injects additional processing into the parsed representation to defer checking of a 1 row condition required by statement semantics. The query engine further injects processing to utilize a result of the additional processing to validate a single row is produced for each GROUPING/PARTITION key. The parsed representation is modified to remove the 1 row condition. The query engine decorrelates the parsed representation using a predetermined method absent a requirement for a unique key to be present in a predicate of the scalar operation.

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Afiya Nusrat