PARTITION ELIMINATION SYSTEM FOR A DATABASE THAT USES A MULTI-LEVEL PARTITIONING DEFINITION
A partition elimination system is provided for a database. The database uses a multi-level partitioning definition. The partition elimination system includes an interface for receiving data indicative of a plurality of level-specific elimination lists. Each list is respectively associated with one of the levels in the definition. A processor is responsive to the data for providing a single combined partition elimination list. Typically the level-specific elimination lists provide a minimum selection of level-specific partition pairs and the combined partition elimination list provides a minimum selection of combined partition pairs.
1 . A partition elimination system for a database that uses a multi-level partitioning definition, the system including:
an interface for receiving data indicative of a plurality of level-specific elimination lists respectively associated with each level in the definition; and
a processor responsive to the data for providing a single combined partition elimination list.
2 . A system according to claim 1 wherein the data is derived from partition elimination on the basis of a query that constrains on one or more level-specific partitions of the database.
3 . A system according to claim 2 wherein each level-specific elimination list identifies one or more level-specific partitions on which the query constrains.
4 . A system according to claim 3 wherein the combined partition elimination list identifies one or more combined partitions on which the query effectively constrains.
5 . A system according to claim 1 either or both of the level-specific elimination lists and the single combined partition elimination list is an inclusive list.
6 . A system according to claim 1 wherein for each level-specific partition in the definition there is defined a level-specific partition number and for each combination of individual partitions there is defined a combined partition number.
7 . A system according to claim 6 wherein the combined partition number is defined on the basis of a predetermined protocol.
8 . A system according to claim 7 wherein the predetermined protocol involves identifying combinations of the level-specific partition numbers and assigning in a logical order a unique combined partition number for each combination.
9 . A system according to claim 6 wherein a unique combination of level-specific partition numbers is mappable to a unique combined partition number.
10 . A system according to claim 1 wherein the processor repeatedly calls a function to identify a pair of combined partitions for inclusion in the combined elimination list, the pair defining a range of combined partitions.
11 . A system according to claim 10 wherein the function is responsive to function state data.
12 . A system according to claim 11 wherein the function modifies the function state data such that a unique result is provided each time the function is called, the unique result either being a unique pair for inclusion in the combined elimination list or a null result indicating that all unique pairs for inclusion in the combined elimination list have been previously identified.
13 . A system according to claim 12 wherein the function includes an identification sub-function for identifying a unique combination of the level specific partitions identified by the level-specific elimination lists for a selection of the levels.
14 . A system according to claim 13 wherein the selection of the levels is from the lowest level to the highest level for which the respective level-specific elimination list excludes one or more level-specific partitions.
15 . A system according to claim 13 wherein each time the identification sub-function is called a unique and not previously considered combination is identified, the sub-function returning null once all unique combinations have been previously identified.
16 . A system according to claim 15 wherein the combinations are identified in increasing combined partition order.
17 . A system according to claim 15 wherein the unique combination is maintained in the data table.
18 . A system according to claim 15 wherein the function includes a mapping sub-function, the mapping sub-function being responsive to the unique combination for identifying the pair of combined partitions.
19 . A system according to claim 17 wherein the mapping function is responsive to the number of contiguous combined partitions for each level in the selection of levels.
20 . A system according to claim 1 wherein the level-specific elimination lists provide a minimum selection of level-specific partition pairs and the combined elimination list provides a minimum selection of combined partition pairs.
21 . A system according to claim 20 wherein the level-specific elimination lists provide level specific pairs in increasing order, and the combined elimination list provides combined partition pairs in increasing order.
22 . A method for partition elimination in a database, the database using a multi-level partitioning definition, the method including the steps of:
receiving data indicative of a plurality of level-specific elimination lists respectively associated with each level in the definition; and
being responsive to the data for providing a single combined partition elimination list.
23 . A combined partition elimination list for a database that uses a multi-level partitioning definition.