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

摘要

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.