Encyclopedia of Database Systems

2018 Edition
| Editors: Ling Liu, M. Tamer Özsu

Flex Transactions

  • Aidong ZhangEmail author
  • Bharat Bhargava
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_726


ConTracts; Flexible transactions; S-transactions


In database systems, a transaction is a sequence of actions performed on data items in a database. In a distributed database environment, a global transaction is a set of subtransactions, where each subtransaction is a transaction accessing the data items at a single local site. The flex transaction model supports flexible execution control flow by specifying two types of dependencies among the subtransactions of a global transaction: (i) execution ordering dependencies between two subtransactions, and (ii) alternative dependencies between two subsets of subtransactions.

Key Points

Flexible transaction models, such as ConTracts, Flex Transactions, S-transactions, and others [1, 2, 3], increase the failure resilience of global transactions by allowing alternate subtransactions to be executed when a local database site fails or a subtransaction aborts. In a non-flexible transaction, a global subtransaction abort is...

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Recommended Reading

  1. 1.
    Wächter H, Reuter A. The ConTract model. In: Elmagarmid AK, editor. Database transaction models for advanced applications. Los Altos: Morgan Kaufmann; 1992.Google Scholar
  2. 2.
    Zhang A, Nodine M, Bhargava B. Global scheduling for flexible transactions in heterogeneous distributed database systems. IEEE Trans Knowl Data Eng. 2001;13(3):439–50.CrossRefGoogle Scholar
  3. 3.
    Zhang A, Nodine M, Bhargava B, Bukhres O. Ensuring relaxed atomicity for flexible transactions in multidatabase systems. In: Proceedings of ACM SIGMOD International Conference on Management of Data; 1994. p. 67–78.Google Scholar

Copyright information

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

Authors and Affiliations

  1. 1.State University of New YorkBuffaloUSA
  2. 2.Purdue UniversityWest LafayetteUSA

Section editors and affiliations

  • Panos K. Chrysanthis
    • 1
  1. 1.Dept. of Computer ScienceUniv. of PittsburghPittsburghUSA