Advertisement

Acta Informatica

, Volume 18, Issue 1, pp 17–30 | Cite as

Optimum reorganization points for arbitrary database costs

  • Raúl J. Ramírez
  • Frank W. Tompa
  • J. Ian Munro
Article
  • 25 Downloads

Summary

The performance deterioration caused by updates to databases or data structures can be overcome by reorganizing the structure from time to time. In previous work, optimal reorganization intervals were determined for linearly increasing deterioration costs and linearly growing reorganization cost. To date only heuristics have been available for non-linear costs, and no work has been published on optimal solutions.

This paper extends previous results by identifying the reorganization points problem as a shortest route problem and by providing a dynamic programming algorithm to find optimal reorganization points when reorganization and deterioration costs are arbitrary. It is shown that our method usesθ(T**2) basic operations andθ(T) space, whereT represents the database lifetime. Furthermore, we note that no algorithm can solve this problem in significantly less time or space. Examples involving linear and non-linear costs are presented and discussed. Finally, the algorithm is modified to find the optimal sequence of reorganizations to be applied in situations where partial reorganizations are possible.

CR categories

D.4.3 F.2.2 G.2.1 H.2.2 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Bellman, R.: Dynamic Programming. Princeton: University Press 1957Google Scholar
  2. 2.
    Dreyfus, S.E., Law, A.M.: The art and theory of dynamic programming. Mathematics in Science and Engineering. Vol. 130. New York: Academic Press 1977Google Scholar
  3. 3.
    Shneiderman, B.: Optimum database reorganization points. Communications of the ACM16, 362–365 (1973)Google Scholar
  4. 4.
    Tuel, W.: Optimum reorganization points for linearly growing files. ACM Transactions on Database Systems.3, 32–40 (1978)Google Scholar
  5. 5.
    Yao, S.B., Das, K.S., Teorey, T.J.: A dynamic database reorganization algorithm. ACM Transactions on Database Systems.1, 159–174 (1976)Google Scholar

Copyright information

© Springer-Verlag 1982

Authors and Affiliations

  • Raúl J. Ramírez
    • 1
  • Frank W. Tompa
    • 1
  • J. Ian Munro
    • 1
  1. 1.Department of Computer ScienceUniversity of WaterlooWaterlooCanada

Personalised recommendations