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System and method for locating log records in multiplexed transactional logs

  • US 7,689,626 B2
  • Filed: 05/31/2002
  • Issued: 03/30/2010
  • Est. Priority Date: 05/31/2002
  • Status: Active Grant
First Claim
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1. In a transactional logging system, a computer-implemented method for locating a log record in a transactional log, the transactional log having a plurality of regions, the log record being associated with a client, the computer-implemented method comprising:

  • receiving a virtual identifier from the client, the virtual identifier identifying the log record in the transactional log;

    wherein each region of the transactional log includes log records and an owner page that includes information about ownership of each of the log records in the region;

    wherein the owner page identifies at least two clients;

    wherein each of the at least two clients is associated with a different application and wherein the transactional log includes log records from the at least two clients;

    associating a first group of log records with an identity of the client in response to receiving the first group of log records from the client;

    associating a second group of log records with an identity of a second client in response to receiving the second group of log records from the second client;

    storing a destination owner page within a destination region of the transactional log, the destination owner page comprising a first range of identifiers associated with the identity of the client and a second range of identifiers associated with the identity of the second client;

    wherein the owner page further includes an owner page physical identifier identifying the location of the owner page in the transactional log;

    determining a correct region in the transactional log from among the plurality of regions by first accessing a presumed region in the transactional log using the virtual identifier and the identity of the client and determining if the presumed region contains the log record by accessing an owner page in the presumed region and determining whether the virtual identifier is within a range of identifiers associated with the identity of the client in the owner page; and

    if the presumed region does not contain the log record then determining the correct region that contains the log record by accessing at least one other region in the transactional log and accessing the owner page for the other region;

    calculating a log block physical identifier associated with the log block containing the log record, the calculation being based on the owner page physical identifier;

    mapping the virtual identifier to the log block physical identifier for the log record in the correct region using the owner page associated with the correct region, the physical identifier corresponding to the location of the log record in the transactional log; and

    locating the log block containing the log record in the transactional log using the log block physical identifier.

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