International Business Machines Corporation

Edward Gust Branish, Ii

James C Sun

George Richard Hughes, Jr

Veerabhadra R Chinnam

Calisto Paul Zuzarte

John Frederick Hornibrook

Dieu Quang La

A method, computer program product, and system for optimizing aggregate queries are provided. The method, computer program product, and system provide for receiving an aggregate query comprising a GROUP BY operation and an aggregate function, creating an access plan for executing the aggregate query, the access plan including a join between an outer relation and an inner relation, and designating the join included in the access plan as an early out join.

Optimization of aggregate queries in database management systems using an early out join when processing min and max functions

A mechanism is provided for secure data access in a data processing system. A database having two tables is provided. A subset of the tables' primary key attributes is considered sensitive. A first user is authorized to access the primary key's sensitive attribute in an unmasked format, while a second user is authorized to access same data in a masked format. Two security views are generated granting the second user access to the primary key's sensitive attribute values of both tables in the masked format. The masked format value is generated from an unmasked format value using a reversible function. A join operation between the two security views is performed by optimizing a query statement corresponding to the join operation.

Secure data access using SQL query rewrites

A mechanism is provided for secure data access in a parallel processing system. A database having two tables is provided. A subset of the tables' primary key attributes is considered sensitive. A first user is authorized to access the primary key's sensitive attribute in an unmasked format, while a second user is authorized to access same data in a masked format. Two security tables are generated having a plurality of entries mapping the values of the primary key attribute in the unmasked format to the values of the primary key attribute in the masked format. A security view is generated joining the two security tables. The security view grants the first user access to the values of the primary key's sensitive attribute in the unmasked format only and grants the second user access to the values of the primary key's sensitive attribute in the masked format only.

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Hanover, NH, United States of America

Edward Gust Branish, Ii