Skip to main content
SpringerLink
Log in
Book cover

Encyclopedia of Database Systems pp 3917–3921Cite as

Temporal Coalescing

  • Reference work entry
  • First Online:

Definition

Temporal coalescing is a unary operator applicable to temporal databases that is similar to duplicate elimination in conventional databases. Temporal coalescing merges value-equivalent tuples, i.e., tuples with overlapping or adjacent timestamps and matching explicit attribute values. Tuples in a temporal relation that agree on the explicit attribute values and that have adjacent or overlapping timestamps are candidates for temporal coalescing. The result of operators may change if a relation is coalesced before applying the operator. For instance, an operator that counts the number of tuples in a relation or an operator that selects all tuples with a timestamp spanning at least 3 months are sensitive to temporal coalescing.

Historical Background

Early temporal relational models implicitly assumed that the relations were coalesced. Ben Zvi’s Time Relational Model [13, Chap. 8], Clifford and Croker’s Historical Relational Data Model (HRDM) [13, Chap. 1], Navathe’s Temporal...

This is a preview of subscription content, log in via an institution.

Chapter
USD   29.95
Price excludes VAT (USA)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever
eBook
USD   4,499.99
Price excludes VAT (USA)
  • Available as EPUB and PDF
  • Read on any device
  • Instant download
  • Own it forever
Hardcover Book
USD   6,499.99
Price excludes VAT (USA)
  • Durable hardcover edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Learn about institutional subscriptions

Recommended Reading

  1. Allen JF. Maintaining knowledge about temporal intervals. Commun ACM. 1983;16(11):832–43.

    Article  MATH  Google Scholar 

  2. Böhlen MH, Snodgrass RT, Soo MD. Coalescing in temporal databases. In: Proceedings of the 22th International Conference on Very Large Data Bases; 1996. p. 180–91.

    Google Scholar 

  3. Böhlen MH, Jensen CS, Snodgrass RT. Temporal statement modifiers. ACM Trans Database Syst. 2000;25(4):48.

    Article  MATH  Google Scholar 

  4. Celko J. SQL for smarties: advanced SQL programming. San Francisco: Morgan Kaufmann; 1995.

    MATH  Google Scholar 

  5. Leung C, Muntz R. Query processing for temporal databases. In: Proceedings of the 6th International Conference on Data Engineering; 1990. p. 200–8.

    Google Scholar 

  6. Leung TYC, Pirahesh H. Querying historical data in IBM DB2 C/S DBMS using recursive SQL. In: Clifford J, Tuzhilin A, editors. Recent advances in temporal databases. Berlin: Springer; 1995.

    Google Scholar 

  7. Lorentzos N, Johnson R. Extending relational algebra to manipulate temporal data. Inf Syst. 1988;15(3):289.

    Article  MATH  Google Scholar 

  8. Lorentzos NA, Mitsopoulos YG. Sql extension for interval data. IEEE Trans Knowl Data Eng. 1997;9(3):480–99.

    Article  MATH  Google Scholar 

  9. Sadeghi R, Samson WB, Deen SM. HQL – a historical query language. Technical report, Dundee College of Technology, Dundee, September 1987.

    Google Scholar 

  10. Snodgrass RT. The temporal query language TQuel. ACM Trans Database Syst. 1987;12(2):247–98.

    Article  MathSciNet  Google Scholar 

  11. Snodgrass RT, editor. The TSQL2 temporal query language. Boston: Kluwer; 1995.

    MATH  Google Scholar 

  12. Snodgrass RT. Developing time-oriented database applications in SQL. San Mateo: Morgan Kaufmann; 2000.

    Google Scholar 

  13. Tansel A, Clifford J, Gadia S, Jajodia S, Segev A, Snodgrass RT. 1Temporal databases: theory, design, and implementation. Redwood City: Benjamin/Cummings; 1993.

    Google Scholar 

  14. Zhou X, Wang F, Zaniolo C. Efficient temporal coalescing query support in relational database systems. In: Proceedings of the 17th International Conference Database and Expert System Applications; 2006. p. 676–86.

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Free University of Bozen-Bolzano, Bozen-Bolzano, Italy

    Michael H. Böhlen

  2. University of Zurich, Zürich, Switzerland

    Michael H. Böhlen

Authors
  1. Michael H. Böhlen
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Michael H. Böhlen .

Editor information

Editors and Affiliations

  1. Georgia Institute of Technology College of Computing, Atlanta, GA, USA

    Ling Liu

  2. University of Waterloo School of Computer Science, Waterloo, ON, Canada

    M. Tamer Özsu

Section Editor information

  1. University of Arizona, Tucson, AZ, USA

    Richard T. Snodgrass

  2. Aalborg University, Aalborg Øst, Denmark

    Christian S. Jensen

Rights and permissions

Reprints and permissions

Copyright information

© 2018 Springer Science+Business Media, LLC, part of Springer Nature

About this entry

Check for updates. Verify currency and authenticity via CrossMark

Cite this entry

Böhlen, M.H. (2018). Temporal Coalescing. In: Liu, L., Özsu, M.T. (eds) Encyclopedia of Database Systems. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-8265-9_388

Download citation

Publish with us

Policies and ethics

Search

Navigation