Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
2007-11-06
2007-11-06
Rimell, Sam (Department: 2164)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000
Reexamination Certificate
active
10162731
ABSTRACT:
An optimistic, latch-free index traversal (“OLFIT”) concurrency control scheme is disclosed for an index structure for managing a database system. In each node of an index tree, the OLFIT scheme maintains a latch, a version number, and a link to the next node at the same level of the index tree. Index traversal involves consistent node read operations starting from the root. To ensure the consistency of node read operations without latching, every node update operation first obtains a latch and increments the version number after update of the node contents. Every node read operation begins with reading the version number into a register and ends with verifying if the current version number is consistent with the register-stored version number. If they are the same, the read operation is consistent. Otherwise, the node read is retried until the verification succeeds. The concurrency control scheme of the present invention is applicable to many index structures such as the B+-tree and the CSB+-tree.
REFERENCES:
patent: 6009425 (1999-12-01), Mohan
patent: 6272465 (2001-08-01), Hewitt et al.
patent: 6317819 (2001-11-01), Morton
Cha Sang K.
Hwang Sangyong
Kim Ki-hong
Kwon Keunjoo
Rimell Sam
SAP (AG)
Schwegman, Lundberg & Woessner, P. A.
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