Patent ID: 7490083
Filing Date: 2009-02-10
Classification: G06F,Y10S

Abstract:
1. A method for handling transaction messages in asynchronous data replication in a database system, the database system including a source node and a target node, each transaction message having information concerning a row change to a table copy at the source node, the method comprising: determining whether a first transaction message has a dependency on a preceding non-completed transaction message, the first transaction message having a dependency on the preceding non-completed transaction when a row change associated with the preceding non-completed transaction requires application to a table copy at the target node prior to a row change associated with the first transaction message; responsive to the first transaction message having a dependency on the preceding non-completed transaction, releasing the first transaction message and applying the row change associated with the first transaction message to the table copy at the target node; and responsive to the first transaction message not having a dependency on the preceding non-completed transaction, applying the row change associated with the first transaction message to the table copy at the target node without holding the first transaction message, wherein determining whether the first transaction message has a dependency on the preceding non-completed transaction message comprises comparing a new replication key value in the row change in the first transaction message to an old replication key value of a row change in the preceding non-completed transaction message, including comparing a hash value of the new replication key value in the row change in the first transaction message to a hash value of the old replication key value in the row change in the preceding non-completed transaction message; and