Decomposed query conditions
A method, article of manufacture and apparatus for decomposing an initial query into smaller conditional groups for execution on a database is disclosed. A separate database query may be generated for each of the conditional groups, and the results of executing these separate database queries may be combined and returned as the result of the initial query. Typically, the initial query may be decomposed because it is otherwise too large and/or too complex to be executed directly.
1. A method of executing a primary query on a database contained within a database system, comprising:
decomposing the primary query into a plurality of conditional groups, wherein each conditional group is a fragment of the primary query, and wherein the conditional groups are logically related to one another;
generating a secondary query for each of the two or more conditional groups;
executing at least one of the secondary queries;
combining the results of the secondary queries based on the logical relationships between the conditional groups; and
returning the combined results of the secondary queries as the result of the primary query.
2. The method of claim 1 , wherein the primary query is decomposed into conditional groups after the query is optimized.
3. The method of claim 1 , wherein the database system uses the logical relationships between the conditional groups to determine an order of execution of the secondary queries.
4. The method of claim 3 , wherein at least one secondary query is evaluated using results of an earlier performed secondary query.
5. The method of claim 1 , further comprising optimizing the conditional groups prior to executing the secondary queries, wherein the conditional groups are optimized for one or more of efficiency, table usage, properties of the database system, and properties of data in the database.
6. The method of claim 1 , wherein logical relationship between two conditional groups comprises an AND or OR logical relationship.
7. The method of claim 1 , wherein the primary query is too logically complex to be executed directly by the database system.
8. The method of claim 1 , wherein the primary query is too large in size to be executed directly by the database system.
9. The method of claim 1 , wherein combining the results of the secondary queries performing an overquery on the results of the secondary queries, wherein the overquery is evaluated using the results of the one or more secondary queries.