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公开(公告)号:CA2249080A1
公开(公告)日:2000-03-25
申请号:CA2249080
申请日:1998-09-25
Applicant: IBM CANADA
Inventor: WINER MICHAEL J , HOP HING NELSON , HURAS MATTHEW A , LINDSAY BRUCE G , ROMANUFA KERILEY K , GOSS JEFFREY J
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.
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公开(公告)号:CA2384185A1
公开(公告)日:2003-10-29
申请号:CA2384185
申请日:2002-04-29
Applicant: IBM CANADA
Inventor: ROMANUFA KERILEY K , SACHEDINA AAMER , HURAS MATTHEW A
Abstract: A hash table is provided in which identifying properties of the data items pointed to by the hash table are selected and are included within the hash table buckets. The properties recorded in the buckets are able to be stored in a cache for the hash table and are used to located data items pointed to by the hash table. The hash table has bucket groups defining a second level hash table. The bucket groups are used to permit resizing of the hash table. Each bucket group has a latch so that that exclusive access for the resizing operation is obtainable on a group by group basis.
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公开(公告)号:CA2353017A1
公开(公告)日:2003-01-12
申请号:CA2353017
申请日:2001-07-12
Applicant: IBM CANADA
Inventor: LI JOHN , HURAS MATTHEW A , SACHEDINA AAMER , ROMANUFA KERILEY K , SCHLAMB KELLY W , ZHENG ROGER L
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公开(公告)号:CA2433254A1
公开(公告)日:2004-12-25
申请号:CA2433254
申请日:2003-06-25
Applicant: IBM CANADA
Inventor: HURAS MATTHEW A , SACHEDINA AAMER , ROMANUFA KERILEY K
Abstract: A system and method for warm shutdown and restart of a buffer pool is provided. The buffer content including pages and control structures associated with these pages i s partitioned into blocks and each block is saved to disk as a sequential file. The size of eac h block may be selected to provide the optimal I/O (input/output) efficiency during buffer pool shutdown and restart operations. Blocks can be saved simultaneously using a number of writer threads. During restart of the buffer pool, the control information is read from the disk an d restored to the buffer pool using reader threads. The buffer pool may be made available for references to pages while reader threads are enabled to read the saved information by blocks to facilitate a more rapid restoration of information in the buffer pool. Allocation of portions of the buffer pool for restoring pages may be performed while the buffer pool is available for references to hasten availability.
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公开(公告)号:CA2306969A1
公开(公告)日:2001-10-28
申请号:CA2306969
申请日:2000-04-28
Applicant: IBM CANADA
Inventor: HURAS MATTHEW A , ROMANUFA KERILEY K , SACHEDINA AAMER
Abstract: A computer system dynamically scales back latch requests for system resource s. Tasks seeking access to system resources each dynamically determine the probability that t he task will gain access to the latch relating to a given system resource. Where the task estimates that its probability is below a defined threshold, the task will suspend itself for a defined sleep time. The task dynamically adjusts the length of the sleep time based on the number of times the task enters the suspended state and on the relative changes in the estimated probability that the task will gain access to the resource.
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公开(公告)号:CA2422161C
公开(公告)日:2009-10-06
申请号:CA2422161
申请日:2003-03-14
Applicant: IBM CANADA
Inventor: WINER MICHAEL J , LAU LEO TAT MAN , BERKS ROBERT T , ROMANUFA KERILEY K , FLASZA MIROSLAW A , HURAS MATTHEW A , SACHEDINA AAMER
Abstract: The use of a centralized version table allows for efficient object switching . Rather than synchronizing all database agents to recognize a newly created file as containing the most recent version of a given object, database agents requiring access to t he given object need only consult the centralized version table to learn file identity information. That is, the database agents consult the centralized version table to determine which of the files associated with a given object contain the most recent version of the given object. Mechanisms associated with the use of the centralized version table also provide for efficient recovery from a failure that has occurred during an object switchi ng transaction.
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公开(公告)号:CA2422176C
公开(公告)日:2009-07-21
申请号:CA2422176
申请日:2003-03-14
Applicant: IBM CANADA
Inventor: ZHENG ROGER L Q , MCINNIS DALE M , WINER MICHAEL J , MCARTHUR CATHERINE S , HURAS MATTHEW A , GOSS JEFFREY J , ROMANUFA KERILEY K
IPC: G06F16/11
Abstract: A method and system for suspending log-based updating of a database in a manner that permits its resumption without restore, to permit efficient alternation between a log-based update mode and a database access mode. Unplayed log records are protected, as re versions of database pages at a time when the log-based update was suspended. This permits log-based updating to resume where it left off. In order to ensure consistent data for access, a roll-back procedure creates consistent data pagers that are us ed for access, and discarded when log-based update resumes.
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公开(公告)号:CA2438366A1
公开(公告)日:2005-02-26
申请号:CA2438366
申请日:2003-08-26
Applicant: IBM CANADA
Inventor: ROMANUFA KERILEY K , SACHEDINA AAMER , HURAS MATTHEW A
Abstract: For an information retrieval system coupled to a buffer pool maintaining a plurality of pages of recently accessed information for subsequent re-access , there is provided a method of starting the buffer pool. The method facilitates a quicker start to the buffer pool by deferring allocation of page storing portions, for example, until they ar e needed. The method comprises making the buffer pool available for storing pages while deferring allocation of a page storing portion of the buffer pool; and allocating the page storing portion of the buffer pool in response to a demand to store pages to the buffer pool . The method may be used to re-start a buffer pool with pages stored to a memory coupled to t he information retrieval system where the pages where stored upon a buffer pool shutdown. Further, buffer pool readers or prefetchers may be configured to read pages for storing to t he buffer pool and allocate the page storing portions of the buffer pool in response to instructions to read particular pages.
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公开(公告)号:CA2422176A1
公开(公告)日:2004-09-14
申请号:CA2422176
申请日:2003-03-14
Applicant: IBM CANADA
Inventor: HURAS MATTHEW A , MCINNIS DALE M , WINER MICHAEL J , MCARTHUR CATHERINE S , GOSS JEFFREY J , ZHENG ROGER L Q , ROMANUFA KERILEY K
Abstract: A method and system for suspending log-based updating of a database in a manner that permits its resumption without restore, to permit efficient alternation between a log-based update mode and a database access mode. Unplayed log records are protected, as re versions of database pages at a time when the log-based update was suspended. This permits log-based updating to resume where it left off. In order to ensure consistent data for access, a roll-back procedure creates consistent data pagers that are used for access, and discarded when log-based update resumes.
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公开(公告)号:CA2422161A1
公开(公告)日:2004-09-14
申请号:CA2422161
申请日:2003-03-14
Applicant: IBM CANADA
Inventor: ROMANUFA KERILEY K , HURAS MATTHEW A , WINER MICHAEL J , FLASZA MIROSLAW A , BERKS ROBERT T , LAU LEO TAT MAN , SACHEDINA AAMER
Abstract: The use of a centralized version table allows for efficient object switching. Rather than synchronizing all database agents to recognize a newly created file as containing the most recent version of a given object, database agents requiring access to the given object need only consult the centralized version table to learn file identity information. That is, the database agents consult the centralized version table to determine which of the files associated with a given object contain the most recent version of the given object. Mechanisms associated with the use of the centralized version table also provide for efficient recovery from a failure that has occurred during an object switching transaction.
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