International Business Machines Corporation

Markos Zaharioudakis

Mir Hamid Pirahesh

Roberta Jo Cochrane

Ting Yu Leung

Yang Sun

George Lapis

Guy Maring Lohman

David Everett Simmen

Ronald Jason Barber

Calisto Paul Zuzarte

Chandrasekaran Mohan

Peter Haas

Kevin Scott Beyer

Michael Jeffrey Winer

Gary Valentin

Steven John Watts

Monica Sachiye Urata

Daniel Costante Zilio

Amit Radheshyam Somani

Hamid Pirahesh

Kit Man Cheung

Samuel S Lightstone

Ashutosh Vir Vikram Singh

David Mark Herbert

Mark A Paskin

A method, apparatus, and article of manufacture for optimizing database queries using an automatic summary table. A query is analyzed using matching and compensation tests between the query at least one correlated subquery within the query and the automatic summary table to determine whether expressions occurring in the query, but not in the automatic summary table, can be derived using the automatic summary table. If so, the query is rewritten so that the automatic summary table is used.

Matching and compensation tests for optimizing correlated subqueries within query using automatic summary tables

The invention herein provides method and apparatus, including software for determining a set of materialized views or indices of the contents or a subset of the contents of a database in a data processing system to be created for one or more users of the database. The method and apparatus provide method and means for evaluating a workload presented by a user to the database; evaluating the data processing system characteristics; evaluating the database characteristics; and, using the above evaluations for recommending a set of suitable materialized views or indices to the user. Another aspect of the invention, which may be used for a workload presented by a user of a database in a data processing system, provides method and apparatus, including software for determining a set of materialized views or indices of the contents or a subset of the contents of the database, by: generating a plurality of materialized view candidates from evaluation of the workload, data processing system characteristics and database characteristics; estimating statistics for the materialized view candidates such as the number of rows, row size, and column statistics; generating a plurality of potential index candidates by evaluating the workload, data processing system characteristics, database characteristics and the materialized view candidates; and, from the materialized view candidates and index candidates selecting a set of suitable materialized views and/or indices for submission to the user.

Method for recommending indexes and materialized views for a database workload

A system, method and computer readable medium for sampling data from a relational database are disclosed, where an information processing system chooses rows from a table in a relational database for sampling, wherein data values are arranged into rows, rows are arranged into pages, and pages are arranged into tables. Pages are chosen for sampling according to a probability P and rows in a selected page are chosen for sampling according to a probability R, so that the overall probability of choosing a row for sampling is Q=PR. The probabilities P and R are based on the desired precision of estimates computed from a sample, as well as processing speed. The probabilities P and R are further based on either catalog statistics of the relational database or a pilot sample of rows from the relational database.

Efficient sampling of a relational database

A method, apparatus, and article of manufacture for optimizing database queries using a derived summary table, wherein a definition of the summary table is based on a full select statement, including, but not limited to, a derived table involving nested GROUP BY operations and complex HAVING clauses with subqueries or joins, that is materialized in the table and describes how the summary table was derived. A query is analyzed using matching/compensation tests between the query and the definition of the summary table (that is, a query by itself) to determine whether expressions occurring anywhere in the query, but not in the summary table, can be derived using either the content in the summary table alone, or after combining (through some relational operator) the content of the summary table with other base tables, and hence the query is subsumed by or overlaps with the summary table definition.

Analyzing, optimizing and rewriting queries using matching and compensation between query and automatic summary tables

A method, apparatus, and article of manufacture for optimizing database queries using subsumption tests between the query and at least one summary table that comprises a cube index to determine whether an expression in the query can be subsumed in the summary table. The summary table stores at least one materialized view involving at least one GROUP BY operation that computes at least one of the following: (1) a cube, (2) a rollup, (3) a grouping set, and (4) a concatenation of cubes, rollups, grouping sets, and one or more grouping items. When the expression in the query can be subsumed in the summary table, the query is rewritten to use the summary table.

Cube indices for relational database management systems

A method, apparatus, and article of manufacture for providing transaction control for a computer-implemented database management system. The database management system manages one or more databases, wherein each of the databases contains one or more documents and each document contains one or more objects. The database management system also supports a file cache for those databases. A transaction control system provides transaction control for the databases, documents, and objects managed by the database management system, wherein the transaction control system monitors and controls the file cache to ensure that modified objects are stored on a data storage device in manner that reflects an accurate status for a log file maintained by the transaction control system.

Data recovery in a transactional database using write-ahead logging and file caching

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Los Gatos, CA, United States of America

Markos Zaharioudakis