International Business Machines Corporation

Akiko Hoshikawa

Shuo Li

Xiaobo Wang

Allan Benjamin Lebovitz

Leilei Li

Hubertus Franke

Ping Wang

Sheng Yan Sun

Jing Wang

Hong Min

Yefim Shuf

Akira Shibamiya

Christopher John Crone

Trace processing in a database system is facilitated by obtaining database trace data collected from database tracing a database system, and data analyzing, by one or more processors, the database trace data to determine one or more field-related rules to, in part, reduce impact on system performance of database tracing in the database system. Trace processing is further facilitated by applying the one or more field-related rules to a database trace in the database system to adjust trace fields of the database trace according to the one or more field-related rules, thereby reducing impact on system performance of the database trace in the database system.

Data-analysis-based facility for adjusting trace fields of a database trace

An improved database-management system determines that a near-capacity leaf page of its database index must be split into multiple pages in order to store newly added index entries. The system determines whether the page should be 'multi-split' into more than two pages, the total number of new pages to be added, and the range of indexed values assigned to each new page. These determinations are made as functions of the frequency with which the index page, and other index pages for the same index, have been split in the past, of the data distribution of values indexed by the leaf page, and of the degree of sequentiality of entries added to the leaf page. Leaf pages approaching capacity may also be scheduled for 'pre-split' splitting during a period of lower utilization. These multi-split and pre-split operations reduce the numbers of index splits and of corresponding synchronous database-log writes.

Multi-page splitting of a database index

A sequence of one or more input objects are sorted by identifying a property that is exhibited by a sequence of one or more input objects, determining whether each input object from the sequence of one or more input objects exhibits the property, storing each of the one or more input objects into a buffer, wherein an input object is stored in a first buffer if it exhibits the property and an input object is stored in a second buffer if it does not exhibit the property, sorting each of the one or more input objects in each buffer, and merging the one or more input objects in each buffer into a sequence of one or more input objects.

Method for sorting data

A method for fetching an ordered first N rows of a table, includes: reading a row in the table; determining that the read row qualifies as the first N rows of the table for rows read so far, and storing data of the read row; and determining an order of data of qualifying rows and storing the order. Only data in rows that qualify to be among the first N rows are ordered and stored. This provides a significantly more efficient processing. It eliminates tournament tree sorts, corresponding work file read and write I/O's, and associated CPU time. This reduces the time for the running of a query and improves the performance of other applications sharing the use of work files. Further, the improved performance is particular significant when the buffer sizes are within a page of records or rows, although multiple pages may be used.

Fast select for fetch first N rows with order by

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Akiko Hoshikawa