A lock technique for disjoint and non-disjoint complex objects

  • U. Herrmann
  • P. Dadam
  • K. Küspert
  • E. A. Roman
  • G. Schlageter
Session 6: Complex Objects

DOI: 10.1007/BFb0022173

Part of the Lecture Notes in Computer Science book series (LNCS, volume 416)
Cite this paper as:
Herrmann U., Dadam P., Küspert K., Roman E.A., Schlageter G. (1990) A lock technique for disjoint and non-disjoint complex objects. In: Bancilhon F., Thanos C., Tsichritzis D. (eds) Advances in Database Technology — EDBT '90. EDBT 1990. Lecture Notes in Computer Science, vol 416. Springer, Berlin, Heidelberg

Abstract

Using database systems in the field of non-standard applications like engineering, robotics, etc. leads to many new requirements. Some of the major ones are support of (disjoint and non-disjoint) complex objects and of long transactions. These requirements disclose severe drawbacks of traditional concurrency control techniques: Transactions are either serialized unnecessarily or the concurrency control overhead grows drastically. Furthermore, traditional lock protocols cannot be applied in a straightforward way to non-disjoint complex objects.

In this paper, a new concurrency control technique is proposed which is derived from the well-known DAG-locking mechanism of System R. The proposed technique avoids most disadvantages of traditional methods. Accesses to non-disjoint complex objects and to their common data can be properly synchronized. Furthermore, a high degree of concurrency with acceptable overhead is achieved on disjoint and non-disjoint, non-recursive complex objects. All this is attained by the use of appropriate lock granules within the structure of complex objects, by a special protocol for requesting locks, and by the anticipation of lock escalations. Lock granules within the structure of complex objects are represented in object-specific lock graphs; query-specific lock graphs show the anticipation of lock escalations. The benefits of the proposed technique are evaluated qualitatively.

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Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • U. Herrmann
    • 1
    • 2
  • P. Dadam
    • 1
  • K. Küspert
    • 1
  • E. A. Roman
    • 1
  • G. Schlageter
    • 2
  1. 1.IBM Heidelberg Scientific CenterHeidelberg
  2. 2.Department of Computer ScienceUniversity of HagenHagen

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