, Volume 2, Issue 1–4, pp 1–26 | Cite as

A cautious scheduler for multistep transactions

  • Naoki Katoh
  • Tiko Kameda
  • Toshihide Ibaraki


Given a classC of serializable schedules, a cautiousC-scheduler is an on-line transaction scheduler that outputs schedules in classC and never resorts to rollbacks. Such a scheduler grants the current request if and only if the partial schedule it has granted so far, followed by the current request, can be extended to a schedule inC. A suitable extension is searched among the set of all possible sequences of the pending steps, which are predeclared by the transactions whose first requests have already arrived. If the partial schedule cannot be extended to a schedule inC, then the current request is delayed. An efficient cautiousCPSR-scheduler has been proposed by Casanova and Bernstein.

This paper discusses cautiousWRW-scheduling, whereWRW is the largest polynomially recognizable subclass of serializable schedules currently known. Since cautiousWRW-scheduling is, in general, NP-complete as shown in this paper, we introduce, a subclass (namedWRW #) ofWRW and discuss an efficient cautiousWRW #-scheduler. We also show that the fixed point set of the cautiousWRW #-scheduler properly containsCPSR. Therefore, ourWRW #-scheduler allows more concurrency than anyCPSR- scheduler.

Key words

Database systems Concurrency control Serialized ability Transaction scheduler 


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  1. [1]
    P. A. Bernstein, D. W. Shipman, and S. W. Wong, Formal aspects of serializability in database concurrency control,IEEE Trans. Software Engrg.,SE-5, 3 (May 1979), 203–216.CrossRefMathSciNetGoogle Scholar
  2. [2]
    G. N. Buckley and A. Silberschatz, Obtaining progressive protocols for a simple multiversion database model,Proc. 9th Int. Conf. on VLDB, Oct/Nov 1983, pp. 74–80.Google Scholar
  3. [3]
    M. J. Carey, The performance of concurrency control algorithms for database management systems, Computer Sciences Tech. Rept. No. 530, University of Wisconsin, Madison, 1984.Google Scholar
  4. [4]
    M. A. Casanova and P. A. Bernstein, General purpose schedulers for database systems,Acta Inform.,14 (1980), 195–220.MATHCrossRefMathSciNetGoogle Scholar
  5. [5]
    M. A. Casanova, The concurrency control problem for database systems, Lecture Notes in Computer Science, Vol. 116, Springer-Verlag, Berlin, 1981.Google Scholar
  6. [6]
    M. R. Garey and D. S. Johnson,Computers and Intractability-A Guide to the Theory of NP-Completeness, Freeman, San Francisco, 1979.MATHGoogle Scholar
  7. [7]
    T. Ibaraki, T. Kameda, and T. Minoura, Serializability made simple, Tech. Rept. LCCRTR82-12, Department of CS, Simon Fraser University, Burnaby, BC, Dec. 1982.Google Scholar
  8. [8]
    T. Ibaraki, T. Kameda, and T. Minoura, Disjoint-interval topological sort: a useful concept in serializability theory,Proc. 9th Int. Conf. on VLDB, Oct/Nov 1983, pp. 89–91.Google Scholar
  9. [9]
    T. Ibaraki, T. Kameda, and N. Katoh, Cautious transaction schedulers for database concurrency control, LCCR Tech. Rep. 85-6, Laboratory for Computer and Communications Research, Simon Fraser University, Burnaby, BC, 1985.Google Scholar
  10. [10]
    N. Katoh, T. Ibaraki, and T. Kameda, Cautious transaction schedulers with admission control,ACM Trans. Database Systems,10, 2 (June 1985), 205–229.MATHCrossRefGoogle Scholar
  11. [11]
    H. T. Kung and C. H. Papadimitriou, An optimality theory of concurrency control for databases,Proc. ACM-SIGMOD Int. Conf. on Management of Data, Boston, May 1979, pp. 116–126.Google Scholar
  12. [12]
    C. H. Papadimitriou, The serializability of concurrent database updates,J. Assoc. Comput. Mach.,26, 4 (Oct. 1979), 631–653.MATHMathSciNetGoogle Scholar
  13. [13]
    C. H. Papadimitriou, A theorem in database concurrency control,J. Assoc. Comput. Mach.,29, 4 (Oct. 1982), 998–1006.MATHMathSciNetGoogle Scholar
  14. [14]
    R. Sethi, A model of concurrent database transactions,Proc. 22nd IEEE Symp. Foundation of Comp. Sci., Oct. 1981, pp. 175–184.Google Scholar
  15. [15]
    R. Sethi, Useless actions make a difference: Strict serializability of database updates,J. Assoc. Comput. Mach.,29, 2 (April 1982), 394–403.MATHGoogle Scholar
  16. [16]
    M. Yannakakis, Issues of correctness in database concurrency control by locking,Proc. ACM Symp. Theory of Computing, May 1981, pp. 363–367.Google Scholar

Copyright information

© Springer-Verlag New York Inc. 1987

Authors and Affiliations

  • Naoki Katoh
    • 1
  • Tiko Kameda
    • 2
  • Toshihide Ibaraki
    • 3
  1. 1.Department of Management ScienceKobe University of CommerceKobeJapan
  2. 2.School of Computing ScienceSimon Fraser UniversityBurnabyCanada
  3. 3.Department of Applied Mathematics and PhysicsKyoto UniversityKyotoJapan

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