Transaction consistent content replication
View Patent ↗Exemplary embodiments of the present invention relate to methodologies, computer program products and systems for the support of content replication, wherein transaction-level data replication consistency is guaranteed. Further, the exemplary methodologies of the present invention can be implemented while incurring little or no additional I/O overhead.
1. A computer program product that includes a computer readable medium useable by a processor, the medium having stored thereon a sequence of instructions which, when executed by the processor, causes the processor to perform transactional consistent data content replication operation, by:
replicating at least one data object from a first server to a second server; wherein the data object is annotated with meta-data, the meta-data comprising transaction identification information;
storing in a mapping table a mapping between a transaction identifier and a commit sequence number, the commit sequence number being a monotonically incrementing number matching order transactions as they are committed;
applying updates to the data object, wherein respective updated data objects comprise a data object change set;
delivering the updated data object to a database, wherein the updated data object is associated with the data object change set;
delivering a current image and a current transaction identifier of the updated data object in conjunction with a previous image and a previous transaction identifier of the data object prior to the current updating changes performed upon the data object to a replication accelerator, wherein the current and previous images of the data object comprise data updates and deletions that have been performed upon the data object;
storing the current and previous data object images in memory at the replication accelerator only during a replication session and without storing active changes to the data object in the first server;
receiving a request for the data object change set;
accessing the database and the mapping table to retrieve the change set, the change set detailing updates that have been performed upon the data object since a previous replication operation;
analyzing the mapping table and the previous transaction identifiers of the replication accelerator, where in the event that it is determined that an object comprised within the data consistent change set does not contain proper transactional consistent information then a correct version of the object is retrieved from the replication accelerator only during the replication session and the correct object version is utilized to restore the correct transactional consistent image to the object; and
returning the data object change set in response to the request.
2. A computer program product of claim 1 , wherein accessing the database to retrieve the change set comprises accessing the database using table annotations that have been associated with the data object change set.