Patent ID: 8150812
Filing Date: 2012-04-03
Classification: G06F

Abstract:
1. A computer implemented method of data replication, comprising the steps of: capturing a description of changes to a first data instance, which changes are performed as source transactions at a first data processing system; combining the captured descriptions of change for a plurality of source transactions, to form a batch of source transactions; transmitting the batch of source transactions to a second data processing system, wherein the batch is transmitted to the second data processing system within a message; receiving the transmitted batch at the second data processing system and separating the descriptions of changes from the batch into sets of changes corresponding to their respective source transactions, wherein the message is held in persistent storage at the second data processing system until a check of transaction processed records determines that apply transactions have been completed for all of the plurality of source transactions; and for each separate source transaction, applying the corresponding set of changes to a data replica at the second data processing system as a respective separate apply transaction transforming a memory at the second data processing system to match a memory state of the first data processing system and writing a transaction processed record to indicate completion of the respective apply transaction; a message cleaner process periodically checking the transaction processed records to identify messages for which apply transactions have been completed for all of the respective plurality of source transactions; the message cleaner process checking whether deletion of any of the said identified messages would result in holes in the sequence of messages held in persistent storage; and the message cleaner process then deleting only a subset of said identified messages so as to avoid holes in said sequence of messages.