International Business Machines Corporation

Dengfeng Gao

Thomas Abel Beavin

Guy Maring Lohman

Terence Patrick Purcell

Jae Hwang Lee

Eileen Tien Lin

Mengchu Cai

Jun Rao

Li-Mey P Lee

Shengxi Suo

Ihab F Ilyas

Curt Lee Cotner

Gerald George Kiernan

Yao-Ching Stephen Chen

Walid Rjaibi

Timothy Jon Vincent

Gregory R Stager

Xun Li

Irene C Liu

Liyan Zhou

Harley W Boughton

Yuping Ding

Joyce A Taylor

Eric L Alton

System, method, and computer program product to modify a received query, the received query including a first predicate specifying a comparison operator and a second predicate specifying an IS NULL operator, by replacing the comparison operator of the first predicate with an extended comparison operator, and removing the IS NULL operator from the received query, the extended comparison operator configured to support searching of NULL values in a database management system (DBMS), wherein the extended comparison operator is configured to return rows having column data matching a value predefined to represent NULL values.

Boolean term conversion for null-tolerant disjunctive predicates

According to one embodiment of the present invention, a system processes a database query, and comprises a computer system including at least one processor. The system identifies one or more expressions within the database query utilizing a database object with value masking. Masking requirements are determined for each identified expression and the database object utilized by that identified expression is replicated to provide masked and actual versions of that database object in response to the masking requirements for that expression including masked values and actual values of that database object. The value masking of the database object is applied to the identified expressions within the database query based on the determined masking requirements to produce search results with masked values for the database query. Embodiments of the present invention further include a method and computer program product for processing a database query in substantially the same manner described above.

Query transformation for masking data within database objects

A compilation time estimator provides a quantified estimate of the optimizer compilation time for a given query optimizer. The estimator automates the optimizer to choose the right level of optimization in commercial database systems. The estimator reuses an optimizer's join enumerator to obtain actual number of joins, but bypasses plan generation to save estimation overhead, and maintains a small number of interesting physical properties to estimate the number of plans by using a linear regression model. The estimator uses the number of generated plans to estimate query compilation time.

Estimating the compilation time of a query optimizer

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Dengfeng Gao