Abstract: A system, method, and computer-readable medium for grouping of database object access counts per processing module in a parallel processing system. Each processing module manages an intermediate cache allocated thereto that stores database object access counts local to the respective processing module. The processing modules are configured in a hierarchical configuration. The intermediate caches managed by the processing modules at the lowest level of the configuration are forwarded to a parent processing module and merged with the intermediate cache allocated to the parent processing module. A root processing module merges the intermediate caches received from one or more parent processing modules with the root processing module's intermediate cache to generate a final cache. An objects access count data structure is then generated by the root processing module.

Abstract: A method, computer program, and computer network are disclosed for organizing values of multiple alternative equality conditions between a database column and a set of values. The method includes applying a function to each value to obtain a result for each value. The values are organized into groups where each group includes values with the same result. The values are stored according to the groups. A computer program or database system executes queries that include multiple alternative equality conditions between a database column and a set of values. The database system also includes an optimizer that is configured to apply a function to each value to obtain a result for each value. The values are organized into groups where each group includes values with the same result. The values are stored according to the groups.

Abstract: A method, computer program, and database system are disclosed for optimizing a query of a table based on one or more values in one or more columns of the table. The method includes repeating the following steps for a series of rows in the table and optimizing an execution plan for the query based at least in part on a calculated number of rows per unique value. One or more values for the one or more columns are read. The read values are determined to be different from all previously read values in some cases. When the read values are different, the one or more values are recorded in a data structure corresponding to the result of applying a hash function to the one or more values.

Abstract: A method, computer program, and database system are disclosed for processing a database query that includes one or more expressions. The method includes resolving columns in one or more of the expressions. Expression optimization is performed on one or more of the expressions. Afterward, further query optimization is performed.

Abstract: A method, computer program, and database system are disclosed for querying tables stored on multiple processing modules. The method includes specifying module group characteristics. A plurality of modules corresponding to the module group characteristics are then identified. The identified modules are sampled for statistics concerning at least one table specified in a query. An execution plan for the query is optimized based at least in part on the sampled statistics.

Abstract: A system, method, and computer-readable medium for grouping of database object access counts per processing module in a parallel processing system are provided. Each processing module manages an intermediate cache allocated thereto that stores database object access counts local to the respective processing module. The processing modules are configured in a hierarchical configuration and processing modules at the lowest level of the configuration forward their respective intermediate cache to a processing module configured as a parent to the respective processing module. On receipt of intermediate cache(s) from lower level processing modules, a processing module merges the received intermediate caches with the intermediate cache allocated to the processing module. The process is iteratively repeated until a root processing module receives the intermediate caches from processing modules configured as child nodes thereto.

Abstract: A method, computer program, and computer network are disclosed for transforming multiple alternative equality conditions between a database column and a set of values. The method includes identifying one or more groups of consecutive values in the set. The equality conditions corresponding to values found in one or more of the identified groups are removed. One or more inequality conditions corresponding to the one or more of the identified groups are added.