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Systems and methods for reading only durably committed data in a system that otherwise permits lazy commit of transactions

  • US 7,801,866 B1
  • Filed: 02/20/2004
  • Issued: 09/21/2010
  • Est. Priority Date: 02/20/2004
  • Status: Expired due to Fees
First Claim
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1. A computer-implemented method for reading a changed data page from a memory of a computer system, said method comprising:

  • making a change to a data page in the memory as a result of a transaction performed by the computer system;

    storing data associated with the change in a transaction log buffer in the memory of the computer system, but not immediately flushing the transaction log buffer to a persistent data store;

    marking the changed data page in the memory to indicate on the changed data page that the transaction log buffer has yet to be flushed to the persistent data store;

    processing a subsequent transaction in which a durable read of at least a portion of the changed data page is to be performed, and before reading the changed data page;

    determining whether the changed data page is marked indicating that the transaction log buffer has yet to be flushed to the persistent data store;

    if the changed data page is marked indicating that the transaction log buffer has yet to be flushed to the persistent data store, flushing the transaction log buffer to the persistent data store prior to the changed data page being read;

    unmarking the changed data page when the transaction log buffer is flushed; and

    reading an unmarked data page as part of a read operation that uses data that has been stored in the persistent data store, without first flushing said transaction log buffer.

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