公开(公告)号：CA2369621A1

公开(公告)日：2003-07-25

申请号：CA2369621

申请日：2002-01-25

Applicant: IBM CANADA

Inventor： POSNER SARAH ,  FLASZA MIROSLAW A ,  WINER MICHAEL J ,  ZHENG ROGER L Q ,  HURAS MATTHEW A ,  GOSS JEFFREY J ,  MEADOWCROFT LORYSA M ,  MCARTHUR CATHERINE S

IPC: G06F9/46 ,  G06F12/00 ,  G06F12/14 ,  G06F13/14 ,  G06F17/30

Abstract: The present invention is directed at a method and apparatus for handling resource transaction requests. By marking a waiting transaction request, having an access mode which is incompatible with the access mode of at least one of the executing transactions, with an ignore bit, a subsequent transaction request with an access mode compatible with the access mode(s) of the executing transaction(s) may receive access to the resource. The subsequent transaction request is then marked with a bypass indicator such that when the executing transactions are finished accessing the resource, the waiting transaction request may be notified it may have access to the resource. By including the ignore bit, each subsequent transaction request which arrives after ignore bit has been set, does not suffer from starvation.

公开(公告)号：CA2279092C

公开(公告)日：2002-09-10

申请号：CA2279092

申请日：1999-07-29

Applicant: IBM CANADA

Inventor： CRANSTON LESLIE A ,  MCARTHUR CATHERINE S ,  HURAS MATTHEW A

IPC: G06F17/30

Abstract: A method executed by a data processor for scanning a reverse range. The scan is conducted in an index for a table having an upper end and a lower end. The reverse ran ge has a start key value for defining the reverse range, and the index has a set of keys representing a set of records and record attributes in the table. Each key in the set of keys has a RID designating a record in the table and a key value corresponding to an attribute of the record in the table. The method includes the steps of searching the index for a start key, selecting an upper bound of the reverse range, and, if the upper bound is the first key in the index, indicating that the index does not contain any key value within the reverse range, or, if the upper bound is not the first key in the index, then fetching each key below the upper bound in the index.

公开(公告)号：CA2322613A1

公开(公告)日：2002-04-06

申请号：CA2322613

申请日：2000-10-06

Applicant: IBM CANADA

Inventor： LYLE ROBERT W ,  WINER MICHAEL J ,  SACHEDINA AAMER ,  HURAS MATTHEW A

IPC: G06F9/46 ,  G06F9/50

Abstract: A stealable latch mechanism for programming environments supporting concurre nt tasks. The latch mechanism has a function for providing a latch to a requesting task, a function for a task holding a latch to release the held latch, a function for a task holding a latch to ma rk the held latch stealable, and a function for a task holding a latch marked stealable to mark the latch unstealable where the held latch is not marked stolen by another task. The function for providing a latch to a requesting task provides that the requesting task will receive on request a latch marke d stealable and held by a holding task. Any resources associated with the stealable latch are placed in a consistent state prior to the requesting task accessing the resources.

公开(公告)号：CA2249080C

公开(公告)日：2001-12-04

申请号：CA2249080

申请日：1998-09-25

Applicant: IBM CANADA

Inventor： ROMANUFA KERILEY K ,  HURAS MATTHEW A ,  WINER MICHAEL J ,  GOSS JEFFREY J ,  HOP HING NELSON ,  LINDSAY BRUCE G

IPC: G06F17/30

Abstract: A method for efficiently searching free space in a relational database management system. The method limits the search to a finite number of space map pages in the free space map. If the configured number of space map pages in the free space map are searched and a page with free space is not found for the row, the row is inserted on the last page, or if no space is available on the last page a new page is created and the row is inserted on the new page. New rows are then appended until some predefined amount of space is filled before a search is done again. As a result, insertion of a row into the database management system does not incur the worst-case cost of searching the entire free space map.

公开(公告)号：CA2302981A1

公开(公告)日：2001-09-29

申请号：CA2302981

申请日：2000-03-29

Applicant: IBM CANADA

Inventor： HOP HING NELSON ,  HURAS MATTHEW A ,  GOSS JEFFREY J ,  LINDSAY BRUCE G

IPC: G06F17/30 ,  G06F7/24

Abstract: A database table reorganization is defined to permit online access of the table during the reorganization. Records are reorganized in the database table by vacating records from a defined number of pages and then filling the pages with records in accordance with a desired ordering for the records. Temporary pointers to the new locations of moved records are us ed to prevent table scanner access to the database table from missing or duplicating records whi le scanning the database table during reorganization. Removal of the temporary pointers is synchroniz ed with the completion of scanning of all table scanners that are commenced during a time when records are being moved as part of a vacating or filling step.

公开(公告)号：CA2279028A1

公开(公告)日：2001-01-29

申请号：CA2279028

申请日：1999-07-29

Applicant: IBM CANADA

Inventor： ZHENG ROGER LUO Q ,  WINER MICHAEL J ,  MCINNIS DALE M ,  HURAS MATTHEW A ,  OFER EFFI

IPC: G06F17/00 ,  G06F17/30

Abstract: A database management system having a dropped table recovery flag. If the dropped table recovery flag is on, at the time that a table is dropped an entry will be made in a dropped table history file. The dropped table history file contains a timestamp of the time of table dro p, a unique dropped table identifier, and table definition information. The system includes a command to permit the table space of a dropped table to be restored and rolled forward to the point of t he dropped table drop. The restored and rolled forward dropped table data is written to a flat file. Th e flat file data is loaded into a recreated table in the current table space to recover the dropped table.