Abstract: Various embodiments of a computer-implemented method, database environment and computer program product are provided which off-load the processing of a database operation. A first database is accessible to a first database server, and a second database is accessible to a second database server. Data is replicated from the first database to the second database, wherein the second database is substantially a copy of the first database. The first database server determines whether to off-load a database operation which would access the first database to the second database server. In response to determining to off-load the database operation, a command is sent to the second database server to perform the database operation. In response to receiving the command, the second database server accesses the second database to perform the database operation. A result of the database operation is received from the second database server.

Abstract: Disclosed is a mechanism that can be implemented in database systems to support distributed transactions in heterogeneous systems. Once the transaction manager of a database system implements this mechanism, application developers and vendors can integrate new datasources into the transaction manager of the database system. This would simplify the application design and ensure the integrity of data and interactions. The interface and interactions between the transaction manager and external datasources (both structured and non-structured) conform to X/Open XA standards. Also disclosed is a technique to design the system catalogs for organizing the datasources and instances of the new datasources.

Abstract: Disclosed is a technique for processing predicates in an iterator function. When an iterator function included in a statement is invoked, one or more predicates included in the statement are obtained. The one or more predicates are applied to a row of data. If applying the one or more predicates results in a match, the row of data is returned. If applying the one or more predicates does not result in a match, a search is performed for another row of data for which application of the one or more predicates results in a match. Also disclosed is a technique for processing predicates in which a statement including an iterator function and one or more predicates is received. A qualification descriptor that describes the one or more predicates and one or more functions that are to be used to evaluate the one or more predicates is created. Then, the iterator function is invoked one or more times, until receiving a done indicator from the iterator function.