International Business Machines Corporation

Abhinav Goyal

Calisto Paul Zuzarte

Nattavut Sutyanyong

Wenbin Ma

Ian R Finlay

Robert Neugebauer

Robin Grosman

Afiya Nusrat

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.

Although many techniques provide ways to answer queries very quickly by either avoiding joins and/or aggregation or avoiding expression computations in order to apply filtering predicates, these techniques have significant potential overhead for maintenance, and require a great deal of storage space. The present invention discloses the use of synopsis or zone tables to expressions to provide powerful filtering capabilities to base tables across joins, and aggregations on join results, thus allowing for highly effective region or stride filtering and ordering aggregate ranges to select the most likely candidate tuples for joining to produce top-N or bottom-N result sets for queries.

Expression based synopsis of database tables

Responding to relational database queries (for example, SQL queries) in a new way. More specifically, qualifying queries are written (for example, written by a human individual) in a way so that a join operation precedes a row limiting operation. Notwithstanding the fact that the join operation precedes the row limiting operation, when responding to the query, machine logic (for example, software) performs the row limiting operation before the join operation. This can improve time and processing efficiency.

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Markham, Canada

Abhinav Goyal