Encyclopedia of Database Systems

2009 Edition
| Editors: LING LIU, M. TAMER ÖZSU

Locking Granularity and Lock Types

  • Ralf Schenkel
Reference work entry
DOI: https://doi.org/10.1007/978-0-387-39940-9_834

Synonyms

Locking granularity and lock types

Definition

Databases are usually organized hierarchically, with tablespaces containing tables, which in turn contain records. In multigranularity locking, this organization is exploited for a more efficient lock management by allowing transactions to lock objects of different granularities like tables or records. Thus, instead of locking each record of a table separately, a transaction can lock the complete table. To ensure a correct execution when transactions use different granularities for locking, additional lock modes are introduced to avoid non-serializable executions.

Key Points

Transactions that acquire many locks on small items like records or pages incur a non-negligible performance and memory overhead for managing these locks. Such transactions can benefit from acquiring locks on coarser granules like tables or complete tablespaces, avoiding many fine-grained locks. However, concurrency may be lower due to an increased number of...

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Recommended Reading

  1. 1.
    Jim Gray, Raymond A. Lorie, Gianfranco R. Putzolu, and Irving L. Traiger. Granularity of locks in a large shared data base. In Proc. 1st Int. Conf. on Very Large Data Bases, 1975, pp. 428–451.Google Scholar
  2. 2.
    Gerhard Weikum, and Gottfried Vossen. Transactional Information Systems. Morgan Kaufman, San Francisco, CA, 2002.Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Ralf Schenkel
    • 1
  1. 1.Max-Planck Institute for InformaticsSaarbrückenGermany