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CONTROLLING A MULTI-DATABASE SYSTEM

  • US 20170322993A1
  • Filed: 12/03/2015
  • Published: 11/09/2017
  • Est. Priority Date: 12/08/2014
  • Status: Active Grant
First Claim
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1. A computer-implemented method for controlling a system, the system comprising a source database and a target database,the system being configured to asynchronously replicate data changes of at least one part of the source database to the target database, the asynchronous replication comprising:

  • evaluating, by a capture engine of the system, a log of the source database for identifying un-replicated data changes of the at least one part of the source database,transferring the un-replicated data changes identified by the evaluation to an apply engine of the system, andapplying, by the apply engine, the un-replicated data changes of the at least one part of the source database to the target database,the computer-implemented method comprising;

    detecting a trigger event for initiating a loading of the complete data content of the at least one part of the source database to the target database;

    in response to the trigger event and regardless of a number of log records that the capture engine has not evaluated, triggering the apply engine to stop the applying of the un-replicated data changes of the at least one part of the source database to the target database;

    in response to stopping the applying of the un-replicated data changes of the at least one part of the source database to the target database by the apply engine, triggering an insert of a start load signal into the log of the source database at a current head of log position;

    in response to the insertion of the start load signal and regardless of the number of the log records that the capture engine has not evaluated, initializing the loading of the complete data content of the at least one part of the source database to the target database,wherein during the loading of the complete data content, concurrent write statements are performed and permitted on the at least one part of the source database;

    after the loading of the complete data content is complete, triggering an inserting of an end load signal into the log at a current head of log position;

    while the loading is performed, triggering the capture engine to store all write statements which are executed, according to the log of the source database , on the at least one part of the source database after the start load signal and before the end load signal in a queue;

    after the loading has completed, triggering the apply engine to apply the write statements stored in the queue to the complete data content of the at least one part of the source database having been loaded completely into the target database,wherein the applying of the write statements comprises identifying and skipping all write statements of which resulting data changes were already transferred to the target database by the loading.

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