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Method for providing session consistency guarantees

  • US 5,581,753 A
  • Filed: 09/28/1994
  • Issued: 12/03/1996
  • Est. Priority Date: 09/28/1994
  • Status: Expired due to Term
First Claim
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1. In a database system having a plurality of servers, a plurality of clients, where at least some of said clients may access different servers at different times, including times when said servers contain inconsistent data values;

  • said servers storing weakly consistent replicated data;

    said data being accessible and updatable by said clients; and

    said data, once updated, being propagated by servers having said updated data to servers that do not have said updated data;

    a method for providing relevant consistency guarantees for said data to every client participating in any session on a per session basis with respect to access and update requests belonging to each respective session, the steps of said method comprising;

    A) defining a plurality of sessions, such that each of said sessions is composed of database access and update requests of at least one client;

    B) selecting a client specified relevant subset of consistency guarantees for each session from a set of predefined, mutually distinguishable guarantees, where the relevancy of a given guarantee is decided by at least one of said clients; and

    C) enforcing the selected guarantees for said at least one client during the course of said session even when said at least one client accesses different servers during the session.

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