Consistent read in a distributed database environment

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US007334004B2

United States Patent

Ganesh et al.

(io) Patent No.: (45) Date of Patent:

US 7,334,004 B2 Feb. 19, 2008

CONSISTENT READ IN A DISTRIBUTED
DATABASE ENVIRONMENT

Inventors: Amit Ganesh, San Jose, CA (US);

Roger J. Bamford, Woodside, CA (US)

Assignee: Oracle International Corporation,

Redwood Shores, CA (US)

Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 526 days.

Appl. No.: 10/119,672

Filed: Apr. 9, 2002

Prior Publication Data

US 2002/0194206 Al Dec. 19, 2002

Related U.S. Application Data

Provisional application No. 60/295,104, filed on Jun. 1, 2001.

Int. CI.

G06F17/30 (2006.01)

U.S. CI 707/203; 707/201; 707/200

Field of Classification Search 707/100,

707/104.1, 200-205 See application file for complete search history.

References Cited

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(Continued)

FOREIGN PATENT DOCUMENTS

EP 0 501 180 A 9/1992

(Continued)

OTHER PUBLICATIONS

Michael Teschke and Achim Ulbrich. Concurrent Warehouse Maintenance Without Comprising Session Consistency. Pub. 1998.*

(Continued)

Primary Examiner—Neveen Abel-Jalil

(74) Attorney, Agent, or Firm—Hickman, Palermo, Truong

& Becker LLP; Christian A. Nichole

Techniques are provided for determining which data item version to supply to a query. According to the techniques, the determination is made by associating a new field, which indicates the time a data item version was current, with each data item version; associating a new field with each query, which indicates the last change that the query must see made by the transaction to which the query belongs; and determining which data item version to use to answer the query based, in part, on a comparison between the values of the two new fields.

18 Claims, 5 Drawing Sheets

U.S. PATENT DOCUMENTS

6,574,717 Bl * 6/2003 Ngai et al 711/147

6,839,751 Bl * 1/2005 Dietz et al 709/224

7,024,656 Bl* 4/2006 Ahad 717/116

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FOREIGN PATENT DOCUMENTS

EP 0 501 180 A2 9/1992

OTHER PUBLICATIONS

Costas Vassilakis et al. Implementation of Transaction and Concurrency Control Support in a Temporal DBMS. Information Systems, vol. 23. No. 5. Pub. 1998.*

Paul M. Bober, et al., "On Mixing Queries and Transactions via Multiversion Locking," 1992, IEEE, pp. 535-545.

C. Mohan, et al., "Efficient and Flexible Methods for Lransient Versioning of Records to Avoid Locking by Read-Only Transactions," 1992, ACM SIGMOD-6/92/CA, USA, pp. 124-133. Bober, Paul M., et al., "On Mixing Queries and Transactions via Multiversion Locking", Computer Sciences Department, University of Wisconsin, 1992, pp. 535-545.

Mohan, C, et al., "Efficient and Flexible Methods for Transient Versioning of Records to Avoid Locking by Read-Only Transactions", XP000393583, IBM Almaden Research Center, publication date Feb. 6, 1992, pp. 124-133. Claims, EP02731965.6, 1 page.

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* cited by examiner