Database log capture program that publishes transactions to multiple targets to handle unavailable targets by separating the publishing of subscriptions and subsequently recombining the publishing
First Claim
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1. A method of log-capture replication comprising:
- publishing, by a first log reader, first messages to a plurality of queues, the first messages comprising changes for transactions extracted from a log by the first log reader;
when one of the queues becomes unavailable, launching a second log reader to read and extract from the log, and to publish second messages comprising changes for transactions extracted from the log by the second log reader to the unavailable queue as a catch-up queue; and
when the catch-up queue becomes available and the second log reader reaches the end of the log, transferring the publishing of the second messages for the catch-up queue from the second log reader to the first log reader.
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Abstract
In a method, apparatus, and article of manufacture implementing the method for log-capture based replication, a mainline log reader publishes messages to a plurality of queues. The messages comprise changes for transactions extracted from a log. When one of the queues becomes unavailable, a catch-up log reader is launched to read from the log and to publish messages comprising changes for the transactions extracted from the log by the catch-up log reader, to the unavailable queue. When the unavailable queue becomes available and the catch-up log reader reaches the end of the log, the publishing of the messages for that queue is transferred from the catch-up log reader to the mainline log reader. In another aspect of the invention, the catch-up log reader is terminated.
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Citations
30 Claims
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1. A method of log-capture replication comprising:
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publishing, by a first log reader, first messages to a plurality of queues, the first messages comprising changes for transactions extracted from a log by the first log reader;
when one of the queues becomes unavailable, launching a second log reader to read and extract from the log, and to publish second messages comprising changes for transactions extracted from the log by the second log reader to the unavailable queue as a catch-up queue; and
when the catch-up queue becomes available and the second log reader reaches the end of the log, transferring the publishing of the second messages for the catch-up queue from the second log reader to the first log reader. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A apparatus for log-capture replication comprising:
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a computer having a data storage device connected thereto, wherein the data storage device stores a log; and
one or more computer programs, comprising a first log reader, executed by the computer, for publishing, by the first log reader, first messages to a plurality of queues, the first messages comprising changes for transactions extracted from the log by the first log reader;
when one of the queues becomes unavailable, launching a second log reader to read and extract from the log and to publish second messages comprising changes for transactions extracted from the log by the second log reader to the unavailable queue as a catch-up queue; and
when the catch-up queue becomes available and the second log reader reaches the end of the log, transferring the publishing of the second messages for the catch-up queue from the second log reader to the first log reader. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An article of manufacture comprising a computer program carrier readable by a computer and embodying one or more instructions executable by the computer to perform a method of log-capture replication, the method comprising:
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publishing, by a first log reader, first messages to a plurality of queues, the first messages comprising changes for transactions extracted from a log by the first log reader;
when one of the queues becomes unavailable, launching a second log reader to read and extract from the log and to publish second messages comprising changes for transactions extracted from the log by the second log reader to the unavailable queue as a catch-up queue; and
when the catch-up queue becomes available and the second log reader reaches the end of the log, transferring the publishing of the second messages for the catch-up queue from the second log reader to the first log reader. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification
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Current AssigneeInternational Business Machines Corporation
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Original AssigneeInternational Business Machines Corporation
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InventorsBourbonnais, Serge, Lindsay, Bruce Gilbert, Li, Siqun
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Granted Patent
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Time in Patent OfficeDays
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Field of Search
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US Class Current705/30
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CPC Class CodesG06F 11/2056 by mirroringG06F 16/27 Replication, distribution o...G06F 2201/80 Database-specific techniquesG06Q 40/12 AccountingY10S 707/99938 Concurrency, e.g. lock mana...Y10S 707/99953 Recoverability
