Abstract: A method for handling transaction messages in asynchronous data replication in a database system, in which the database system includes a source node and a target node, and each transaction message has information concerning a row change to a table copy at the source node. The method includes determining whether a first transaction message has a dependency on a preceding non-completed transaction message. Responsive to the first transaction message having a dependency on the preceding non-completed transaction, the method further includes holding the first transaction message, completing the preceding non-completed transaction message including applying the row change associated with the preceding non-completed transaction message to the table copy at the target node, and responsive to completing the preceding non-completed transaction message, releasing the first transaction message and applying the row change associated with the first transaction message to the table copy at the target node.

Abstract: A globally unique transaction identifier for each transaction is recorded in log entries pursuant to a two-phase commit protocol, wherein multiple log entries in multiple database recovery logs that correspond to one transaction have a same globally unique transaction identifier. A causally ordered, ascending timestamp value is maintained in the log entries pursuant to the two-phase commit protocol. For each of the multiple database recovery logs, all the log entries related to a single transaction are marked identically with a mark unique to the single transaction in a given one of the database recovery logs. Global changes are identified for the single transaction from the log entries in the multiple database recovery logs based on the marking and the globally unique transaction identifier for each transaction by reading log entries based on the causally ordered, ascending timestamp value.

Abstract: A method and system for member initialization to and deactivation from an asynchronous data replication group in a database system is disclosed. The method and system allows new members to be added to the replication group or existing members to be removed from the replication group, without requiring the halting of the asynchronous replication of data. The performance advantages of asynchronous replication are still realized during member initialization or deactivation.

Abstract: An automatic initial data load to a new table copy concurrently with active replication to existing table copies in an asynchronous replication group includes: initiating a data load of the new table copy; creating spill queue(s) at the new table copy; loading the data from a source table copy to the new table copy, where changes for the active table copies are applied during the loading, but changes to the new table copy are stored in a spill storage area; applying the changes in the spill storage area to the new table copy after the loading of the data is done; and removing the spill storage area after the changes have been applied to the new table copy. Thus, a new table copy is initialized into the replication group without requiring that replication be suspended at the source or any of the existing table copies during the initializing process.

Abstract: An improved method for providing parallel apply in asynchronous data replication in a database system is disclosed. The improved method and system provides a high speed parallel apply of transactional changes to a target node such that the parallel nature of the application of changes does not compromise the integrity of the data. The method and system detects, tracks, and handles dependencies between transaction messages to be applied to the target node. If a transaction message has a dependency on one or more preceding transaction messages whose applications have not yet completed, that transaction message is held until the application completes. In addition, the method and system requires significantly less overhead than conventional approaches.

Abstract: An improved method and system for preserving data constraints during parallel apply in asynchronous transaction replication in a database system have been disclosed. The method and system preserves secondary unique constraints and referential integrity constraints, while also allowing a high degree of parallelism in the application of asynchronous replication transactions. The method and system also detects and resolves ordering problems introduced by referential integrity cascade deletes, and allows the parallel initial loading of parent and child tables of a referential integrity constraint.

Abstract: A method and system for providing convergence of data copies in asynchronous data replication in a database system, includes: labeling rows of a plurality of table copies with a monotonic number, a copy identification, and propagation controls; asynchronously capturing at least one labeled change to any row of any of the plurality of table copies from a database recovery log; determining that the captured change is to be communicated to others of the plurality of table copies; communicating the captured change to the others of the plurality of table copies; and applying the communicated change to the others of the plurality of table copies, where the plurality of table copies converge to a same state. In applying the communicated changes, conflicting changes are identified and resolved. In this manner, convergence of data copies in asynchronous data replication is provided, and processing and storage costs are significantly reduced.