Abstract: A latent auxiliary database structure constructed for executing a query is automatically saved for reuse in subsequent query execution instances. The latent auxiliary database structure is not maintained concurrently with changes to records in the database tables. If a query execution strategy is subsequently invoked which uses the latent auxiliary database structure, a determination is made dynamically whether to update the previously saved latent structure from database changes recorded in one or more change logs, or to rebuild the latent structure from scratch. Where the cost of updating from the change log is deemed less than the cost of a rebuild from scratch, the previously saved latent structure is updated from the log.

Abstract: A query optimizer optimizes a query to a partitioned database table by determining common characteristics of the partitions and generating a virtual maintained temporary index that spans multiple partitions. Using the virtual maintained temporary index allows the query optimizer to generate an access plan based on the virtual maintained temporary index, which relieves the optimizer from having to individually optimize access to each partition for partitions that share common characteristics.

Abstract: An apparatus, program product and method utilize a query optimizer that identifies Join types in a query plan that can be replaced to facilitate optimization of the plan. If the query plan is considered to have a tree-graph representation, then the optimizer locates Join nodes to be replaced and substitutes an Inner Join node and additional nodes that do not inhibit optimization strategies and algorithms. As a result, all Outer Joins, whether left or right, and all Exception Joins, whether left or right, can be removed from the query plan before performing optimizations such as predicate movement, GROUP BY movement, ORDER BY movement, and Join enumeration.