Abstract: An execution plan of a query for a parallel database system is determined. In one arrangement, the parallel database system is a relational database management system. The execution plan of the query is determined by an optimizer program. Execution plans are inserted into one or more explain tables that are accessible by a visual explain and compare module to display the steps of the execution plan in a graphical user interface. Parallel execution of steps of the execution plan can be depicted in the graphical user interface. Further, plural execution plans for a given query under different conditions may be displayed for comparison.

Abstract: In view of the foregoing, the present invention provides a method and system for improving the operating system to provide benefits to a variety of database management applications and network administration by facilitating deletion of references to published objects that have become unusable, i.e., orphaned. This is enabled by implementing, preferably as part of the operating system, in a separate thread, a module that uses a set of presumptions to detect orphaned objects that can be deleted. Upon detection of suitable orphaned objects the module deletes the orphaned object from the set published objects. This strategy reduces the avoidable overhead associated with publishing objects while improving the performance and stability of the system for longer time periods.