Abstract: A process on a highly distributed parallel computing system is disclosed. When a first compute node in a first pool is ready to hand-off a task to second pool for further processing, the first compute node may first determine whether a node is available in the second pool. If no node is available from the second pool, then the first compute node may begin performing a primary task assigned to the second pool of nodes, up to the point where a service available exclusively to the nodes of the second pool is required. In the interim, however, one of the nodes of the second pool may become available. Alternatively, an application program running on a compute node may be configured with an exception handling routine that catches exceptions and migrates the application to a compute node where a necessary service is available, as such exceptions occur.

Abstract: Embodiments of the invention provide methods, systems, and articles of manufacture for transforming a physical query (e.g., written in SQL) into an abstract query than can be run against an abstract database described by a database abstraction model. In one embodiment, the transformation occurs as a multiple step process: first, transformation of the physical query into an intermediate representation, such as an abstract query plan, and second, transformation of the intermediate representation into an abstract query. There are thousands upon thousands of existing physical (e.g., SQL) queries. Rather than just abandon these existing queries in favor of an abstract database, embodiments of the present invention provide for reverse query processing, that is, for creating an abstract query of the abstract database from a physical query (e.g., an SQL query) of the physical database underlying the abstraction.