International Business Machines Corporation

Bernhard K Schiefer

Arun N Swami

Guy Maring Lohman

Sam Sampson Lightstone

Monica Sachiye Urata

Randall William Horman

Sunil Jeevananda Kamath

Linton B Ward, Jr

Renee J Miller

Robin D Van Boeschoten

Lori G Strain

Said Elnaffar

Jarek Gryz

Pat Martin

Jeff Edmonds

Weipeng P Yan

A method of managing power in a computing system is provided. The method comprises: assessing incoming work; assessing service level agreements related to the incoming work; and coordinating with an operating system layer to control hardware of the computing system based on the service level agreements and a power consumption goal.

Coordinated approach between middleware application and sub-systems

Workload type to be managed by a database management system (DBMS) is a key consideration in tuning the DBMS. Allocations for resources, such as main memory, can be very different depending on whether the workload type is Online Transaction Processing (OLTP) or Decision Support System (DSS). The DBMS also experiences changes in workload type during the normal processing cycle of the DBMS. It would be preferable for the database administrators to recognize the significant shifts of workload type that demand reconfiguring the DBMS to maintain acceptable levels of performance. Disclosed is a workload type classifier module, used by a DBMS, for recognizing workload types so that the DBMS may then manage or adjust its performance and reconfigure its resources accordingly. The classifier may be constructed based on the most significant workload characteristics that differentiate OLTP from DSS. The classifier is then used for identifying changes in workload types contained in a workload.

Method for identifying a workload type for a given workload of database requests

Determining maximal empty rectangles in a binary matrix includes building values in a staircase data structure for each successive entry in the matrix. The values in the staircase data structure are removed where the values correspond to maximal rectangles having the successive entry in the bottom right corner of the rectangle. The values in the staircase data structure for each successive entry being determinable from values in the staircase data structure for a preceding entry in the matrix. The maximal empty rectangles providing a basis for generating efficient relational join operations on defined relational tables.

Efficient determination of homogeneous rectangles in a binary matrix

A join optimizer and method for a relational database management system including a data processor, a stored database, and a plurality of database relations, wherein one or more of the relations are retrieved by the processor by means of query commands by performing a plurality of join operations on the relations, the system employing a general purpose heuristic algorithm which excludes or defers Cartesian products as late in the join sequence as possible, the method includes the steps of determining, in association with the execution of, or preferably prior to executing the general purpose algorithm, whether tables referenced in a query command includes a hub table and at least two encoding tables related to the hub table and, when the query command references a hub table and at least two encoding tables, determining the best access plan for the hub table, determining whether the best access plan utilizes an index used to access the hub table and, if so, constructing a plan to join the encoding tables as Cartesian products, constructing a plan to join the hub table and the encoding tables and storing the plans in the data structures of the optimizer for enumeration with other access plans constructed by the optimizer.

Method for detecting and optimizing queries with encoding/decoding tables

A method of index scanning involves scanning one or more selected indexes and determining the number of data transfers required to traverse all or a portion of a selected index for a selected number of buffer pool sizes. The number of page transfers to scan a whole table of interest versus the number of page transfers to scan each relevant index in accordance with the buffer pool size is determined for a query. The number of page transfers required in proportion to the selectivity of starting and stopping conditions is determined and scaled down in proportion to the selectivity of any starting and stopping conditions present in the search criteria in the query. A suitable correction factor is applied to the number of transfers to account for few rows remaining to be transferred after applying the search criteria, the buffer pool being large, or a low degree of clustering for an index,, as well as accounting for any remaining index sargable search criteria. The search procedures that results in the least number of page transfers in then implemented.

Computer program product for optimizing data retrieval using index

The present invention provides a method for estimating cardinalities for query processing in a relational database management system. The present method is suitable for use with a query optimizer for estimating cardinalities for sets of columns or keys resulting from a grouping operation or a duplicate removal operation.

Method for estimating cardinalities for query processing in a relational

Described herein is a system and method for operating a data processing system having a processing unit and physical storage in which data is stored. The storage is connected to the processing unit for transferring pages of data to the processing unit. The storage contains at least one database table stored on a plurality of pages. Each data base table has a plurality of rows of data, and one or more indexes composed of a sequence of entries which reference the rows. The processing unit has a memory associated with it. A portion of the memory comprises a buffer pool for caching data pages from the table. The method operates by scanning one or more selected indexes in determining the relationship of the number of data transfers required to traverse all or a portion of each selected index for a selected range of buffer pool sizes. Then, a description of this relationship is stored.

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Pickering, Canada

Bernhard K Schiefer