International Business Machines Corporation

Yoichi Tsuji

You-Chin Gene Fuh

Fen-Ling Lin

Li Jun Xia

Shuanglin Guo

Terence Patrick Purcell

Thomas Abel Beavin

Yao-Ching Stephen Chen

Mengchu Cai

Patrick Dooling Bossman

Jerry Mukai

Irene Ching-Hua Liu

Ying Zeng

Chan-Hua Liu

Hsiuying Yen Cheng

Demai Ni

Andrei Fedorovich Lurie

Changjiu Xian

A method and system are presented for quantifying a data page repetition pattern for a database index in a database management system. In one embodiment, the method includes identifying a database index to provide a basis for collecting a data page repetition statistic, the database index having a database index key. The method may also include collecting the data page repetition statistic based on the database index key, wherein the data page repetition statistic quantifies a data page repetition pattern associated with database queries that reference sequential entries of the database index. The method may further include optimizing a data page access process based on the data page repetition statistic. In a further embodiment, the method may utilize both cluster ratio and data page repetition statistics to evaluate data page I/O and CPU cost.

Method and system for quantifying a data page repetition pattern for a database index in a database management system

Techniques are provided that determine that a query includes at least one subquery that may be correlated or decorrelated. An internal representation of the query that represents the subquery in both correlated and decorrelated form is generated, wherein the internal representation includes at least one virtual table.

Cost-based subquery correlation and decorrelation

A method of, a computer program product for and a computer system for managing statistics in a database management system are provided. A value of a volatility of a statistic is determined. A value of a staleness of the statistic is determined using the value of the volatility. A statistics collection task is generated in response to, at least in part, the value of the staleness exceeding a value of a staleness threshold. The statistics collection task is executed to collect an additional value of the statistic. The additional value of the statistic is stored.

Management of database statistics

Provided are a techniques for processing a query including semi-joins. At execution time, a next semi-join is selected from the semi-joins for execution in a current round of semi-join executions. A reporting threshold is determined that indicates a number of record-identifiers to be retrieved for the determined semi-join. The selected semi-join is executed until the determined number of record identifiers are retrieved.

Dynamic semi-join processing with runtime optimization

In various embodiments, a method, apparatus, and article of manufacture collect statistics in a database management system. A workload comprising a plurality of database queries is received. Query statistics for the database queries are identified. The query statistics for the database queries are consolidated to provide consolidated statistics. One or more statistics collection requests are generated based on the consolidated statistics.

Query workload statistics collection in a database management system

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San Jose, CA, United States of America

Yoichi Tsuji