Abstract: A system, computer-implemented method, and computer-program product embodiments for generating an access plan. A query optimizer includes an enumeration method which enumerates a plurality of subsets of a query. Each subset in the query has a plurality of partitions. The partitions of each subset are enumerated into enumerated partitions using at least one thread. For each partition, physical access plans are generated, using at least one thread. Physical access plans are generated in parallel with other physical access plans of different partitions and with other enumerating partitions. The number of threads that perform the enumeration and the generation is dynamically adapted according to a pool of threads available during the enumeration of the partitions and the generation of physical access plans, and a complexity of the query. From the generated physical access plans, a final access plan for the query is determined by choosing the most efficient access plan.

Abstract: Systems, methods and articles of manufacture for determining at least one algorithm from a pool of algorithms to optimize a query. An embodiment includes building optimization blocks for the subplan, determining the complexity of the subplan based on the optimization blocks and selecting an algorithm from a pool of search space generation algorithms based on complexity of the subplan and characteristics of the selected algorithm, and optimizing the subplan with the selected algorithm.

Abstract: Systems, methods and articles of manufacture for determining at least one algorithm from a pool of algorithms to optimize a query. An embodiment includes building optimization blocks for the subplan, determining the complexity of the subplan based on the optimization blocks and selecting an algorithm from a pool of search space generation algorithms based on complexity of the subplan and characteristics of the selected algorithm, and optimizing the subplan with the selected algorithm.