US5764877A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Media recovery with time-split B-trees
Assignee: Hewlett Packard Development Co LP
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Filing: 1995-09-01
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Granted: 1998-06-09
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Expires: 2015-09-01
Abstract
Abstract Modern database systems provide media recovery by taking periodic backups and applying a transaction log to the backup to bring the data up-to-date. A multi-versioned database is one that retains and provides access to historical versions of data. The present invention shows how a history database, supported by the Time-Split B-tree, can be used to also provide the backup function of media recovery. Thus, the same versions used for database history are used for database backup. The cost of taking a backup is comparable to the cost of a good differential backup method, whereby only changed data is backed up. The media recovery cost, especially when the media failure is only partial, e.g., a single disk page, will frequently be lower.
Inventors
- 👤 David Lomet
- 👤 Betty Salzberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:28
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/14; G06F11/1446; G06F11/1448; G06F11/1451; G06F16/00; G06F16/20; G06F16/22; G06F16/2228; G06F16/2246; G06F16/23; G06F16/2308; G06F16/2336; Y; Y10; Y10S; Y10S707/00; Y10S707/99931; Y10S707/99933
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
112 words
For use in a database system, a method of media recovery, comprising the steps of: providing a two-dimensional search structure at least partly defined by nodes and key and time dimensions, such that certain data in the database system is located by traversing the nodes using respective ones of the key and time dimensions, said nodes including history nodes which are periodically written to a secure medium and including current nodes and index nodes; time-splitting into current nodes and history nodes, current nodes having data that has changed and has not been written to the secure medium; and using only the history nodes to recover from an undesired and abnormal system interruption.
Claim 2
Dependent Claim
112 words
For use in a database system, a method of media recovery, comprising the steps of: providing a two-dimensional search structure at least partly defined by nodes and key and time dimensions, such that certain data in the database system is located by traversing the nodes using respective ones of the key and time dimensions, said nodes including history nodes which are periodically written to a secure medium and including current nodes and index nodes; time-splitting into current nodes and history nodes, current nodes having data that has changed and has not been written to the secure medium; and using only the history nodes to recover from an undesired and abnormal system interruption.
Claim 3
Dependent Claim
38 words
A method of media recovery, according to claim 1, wherein the step of using the history nodes includes the step of restoring damaged current nodes by using the history nodes that have the most recent versions of data.
Claim 4
Dependent Claim
26 words
A method of media recovery, according to claim 2, wherein the step of using the history nodes includes the step of providing a media recovery log.
Claim 5
Dependent Claim
26 words
A method of media recovery, according to claim 1, wherein the step of time-splitting is for back-up and does not include making changes to current nodes.
Claim 6
Dependent Claim
23 words
A method of media recovery, according to claim 1, wherein the step of time-splitting includes purging unneeded index terms from the index nodes.
Claim 7
Dependent Claim
23 words
A method of media recovery, according to claim 1, wherein the step of time-splitting includes writing the history node to the secure medium.
Claim 8
Dependent Claim
46 words
A method of media recovery, according to claim 3, further including truncating the media recovery log in response to said step of time splitting so as to remove log records therefrom which are reflected in the history nodes that have been written to the secure medium.
Claim 9
Dependent Claim
28 words
A method of media recovery, according to claim 4, further including using short locks during the step of time-splitting to enhance concurrency and minimize impact database system operation.
Claim 10
Dependent Claim
20 words
A method of media recovery, according to claim 1, wherein the two-dimensional search structure includes a time-split B tree structure.
Claim 11
Dependent Claim
33 words
A method of media recovery, according to claim 1, wherein said certain nodes include index nodes having data or index terms that has changed and has not been written to the secure medium.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-06-08 | 2001-12-08 | 2002-06-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-06-08 | 2005-12-08 | 2006-06-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-06-08 | 2009-12-08 | 2010-06-09 | $7700.00 | Window Closed / Lapsed |