公开(公告)号：CA1285072C

公开(公告)日：1991-06-18

申请号：CA573154

申请日：1988-07-27

Applicant: IBM

Inventor： LEVINE FRANK E ,  MOHAN CHANDRASEKARAN

IPC: G06F12/00 ,  G06F17/30 ,  G06F15/413

Abstract: METHOD FOR CONCURRENT RECORD ACCESS USING AN INDEX TREE A method for fetching key record data in a group of record keys according to at least a portion or a key record through an index tree is provided. The index tree provides concurrent accesses of record keys by different transactions. The index tree includes a root node connected to at least one level of nodes, each node having a key record reference to one of more nodes in a next successive level and having bottom nodes that provide access to the key data. The method consists of the steps of (1) traversing across said nodes from said root node by using said key record portion until a bottom node is reached; (2) limiting all but read accesses to the node being traversed and a previously accessed node, to other concurrent transactions; (3) identifying said key record in said bottom node; (4) limiting all but read accesses to said key record; (5) removing all access limitations to traversed nodes; (6) fetching key record data; and (7) removing the access limitation to the key record after the record data has been fetched. Further, methods for inserting and deleting record keys are provided. Additionally, a method for changing the index tree structure while allowing concurrent accesses to take place is provided.

公开(公告)号：DE69415855D1

公开(公告)日：1999-02-25

申请号：DE69415855

申请日：1994-03-29

Applicant: IBM

Inventor： DIEVENDORFF RICHARD ,  MOHAN CHANDRASEKARAN

IPC: G06F12/02 ,  G06F5/06 ,  G06F9/46 ,  G06F11/00 ,  G06F11/14

公开(公告)号：DE69128367D1

公开(公告)日：1998-01-22

申请号：DE69128367

申请日：1991-02-13

Applicant: IBM

Inventor： MOHAN CHANDRASEKARAN

IPC: G06F9/46 ,  G06F9/52 ,  G06F12/00 ,  G06F15/00 ,  G06F17/30

Abstract: Apparatus and method for reading data pages 33 in a transaction processing system 20 without locking the pages are disclosed. The system maintains a Global_Committed_LSN 36 identifying the oldest uncommitted transaction accessing any of the data, and Object_Committed_LSNs 38a,38b identifying the oldest uncommitted transactions accessing particular files, tables and indexes. Each data page includes a Page_LSN 35 identifying the last transaction to have updated the page. To read a page, a transaction first latches the pages, and compares the page s Page_LSN with the Global_Committed_LSN, or with the page's respective Object_Committed_LSN. If the Page_LSN is older than the Committed_LSN with which is was compared, then the transaction reads the page without locking it, since there can be no uncommitted transaction in process which might have updated the page's data. However if the Page_LSN is younger than the Committed_LSN, the page is locked before being read.

公开(公告)号：GB2276739A

公开(公告)日：1994-10-05

申请号：GB9306662

申请日：1993-03-30

Applicant: IBM

Inventor： DIEVENDORFF RICHARD ,  MOHAN CHANDRASEKARAN

IPC: G06F12/02 ,  G06F5/06 ,  G06F9/46 ,  G06F11/00 ,  G06F11/14

公开(公告)号：DE3889254D1

公开(公告)日：1994-06-01

申请号：DE3889254

申请日：1988-05-10

Applicant: IBM

Inventor： HADERLE DONALD JAMES ,  LINDSAY BRUCE GILBERT ,  MOHAN CHANDRASEKARAN ,  PIRAHESH MIR HAMID ,  SCHWARZ PETER MARTIN

IPC: G06F12/00 ,  G06F11/14

公开(公告)号：BR8901659A

公开(公告)日：1989-11-21

申请号：BR8901659

申请日：1989-04-07

Applicant: IBM

Inventor： LEVINE FRANK ELIOT ,  MOHAN CHANDRASEKARAN

IPC: G06F12/00 ,  G06F17/30 ,  G06F15/40

Abstract: A database system in a data processing system has an index tree structure with a root node having reference keys to nodes in the next lower level and so on until bottom nodes having keys referencing the database records. Multiple users may access the database concurrently. Transactions in which the tree structure is to be modified (for example removal of a record) are performed by traversing the tree to the appropriate bottom node and setting an indication of pendency of the modification. At the same time other accesses to the database, through nodes at which no tree structure modifications are to take place, can continue. When the structure modification has been performed, a log record of it is made to prevent undoing the modification in the event of a system failure, and database access through all the bottom nodes then continues.

公开(公告)号：DE112016000776T5

公开(公告)日：2017-10-26

申请号：DE112016000776

申请日：2016-02-04

Applicant: IBM

Inventor： BHATTACHARJEE BISHWARANJAN ,  SADOGHI HAMEDANI MOHAMMAD ,  MOHAN CHANDRASEKARAN ,  PANDIS IPPOKRATIS ,  RAMAN VIJAYSHANKAR ,  STORM ADAM J ,  BARBER RONALD J ,  LOHMAN GUY M ,  SIDLE RICHARD S

IPC: G06F17/30

Abstract: Ein Verfahren beinhaltet ein logisches Organisieren von Datenobjekten in einer ersten Hierarchie durch einen Objekthierarchieprozessor. Ein Teil der Datenobjekte in der ersten Hierarchie beinhaltet logisch Gruppierungen von anderen Datenobjekten. Der Objekthierarchieprozessor organisiert die Datenobjekte physisch zwischen zwei oder mehr Arten von Arbeitsspeichern in einer zweiten Hierarchie. Ein weiterer Teil der Datenobjekte in der zweiten Hierarchie beinhaltet physisch Gruppierungen von anderen Datenobjekten. Gruppierungen der Datenobjekte in der zweiten Hierarchie werden dynamisch zwischen den zwei oder mehr Arten von Arbeitsspeichern verschoben. Zugriffsebenen der Datenobjekte werden anhand einer Datenstruktur erfasst, die Gruppierungen der Datenobjekte in der ersten Hierarchie auf Metadaten-Informationen wie z. B. kombinierte Zugriffshäufigkeiten der Datenobjekte und eine momentane Anzahl von Zugreifern auf die Datenobjekte in jeder Gruppierung der Datenobjekte abbildet.

公开(公告)号：DE69128367T2

公开(公告)日：1998-06-25

申请号：DE69128367

申请日：1991-02-13

Applicant: IBM

Inventor： MOHAN CHANDRASEKARAN

IPC: G06F9/46 ,  G06F9/52 ,  G06F12/00 ,  G06F15/00 ,  G06F17/30

Abstract: Apparatus and method for reading data pages 33 in a transaction processing system 20 without locking the pages are disclosed. The system maintains a Global_Committed_LSN 36 identifying the oldest uncommitted transaction accessing any of the data, and Object_Committed_LSNs 38a,38b identifying the oldest uncommitted transactions accessing particular files, tables and indexes. Each data page includes a Page_LSN 35 identifying the last transaction to have updated the page. To read a page, a transaction first latches the pages, and compares the page s Page_LSN with the Global_Committed_LSN, or with the page's respective Object_Committed_LSN. If the Page_LSN is older than the Committed_LSN with which is was compared, then the transaction reads the page without locking it, since there can be no uncommitted transaction in process which might have updated the page's data. However if the Page_LSN is younger than the Committed_LSN, the page is locked before being read.

公开(公告)号：SG42807A1

公开(公告)日：1997-10-17

申请号：SG1995002118

申请日：1988-09-21

Applicant: IBM

Inventor： LEVINE FRANK ELIOT ,  MOHAN CHANDRASEKARAN

IPC: G06F12/00 ,  G06F17/30

Abstract: A data base system on a computer uses an index tree containing record keys which reference associated records in the data base. The tree, which comprises a root node extending through intermediate nodes to leaf nodes, provides concurrent accesses to a plurality of users. When changes are to be made to the key structure, action has to be taken to prevent users, other than the user making the change, from corrupting the data or receiving corrupted data. To do this, when one user is inserting or deleting a key and its associated record, all accesses to a node being traversed by this user and the immediately traversed mode are limited to read accesses by other users. At the leaf node, all accesses by others to the key and record being added or deleted are prevented together with accesses to the next successively located record key and its associated record. After the deletion or insertion, the access limitations are removed.

公开(公告)号：DE3854667T2

公开(公告)日：1996-06-20

申请号：DE3854667

申请日：1988-08-03

Applicant: IBM

Inventor： LEVINE FRANK ELIOT ,  MOHAN CHANDRASEKARAN

IPC: G06F12/00 ,  G06F17/30

Abstract: A database system in a data processing system has an index tree structure with a root node having reference keys to nodes in the next lower level and so on until bottom nodes having keys referencing the database records. Multiple users may access the database concurrently. Transactions in which the tree structure is to be modified (for example removal of a record) are performed by traversing the tree to the appropriate bottom node and setting an indication of pendency of the modification. At the same time other accesses to the database, through nodes at which no tree structure modifications are to take place, can continue. When the structure modification has been performed, a log record of it is made to prevent undoing the modification in the event of a system failure, and database access through all the bottom nodes then continues.