16. The one or more hardware memory devices of claim 10 , wherein the property matching component further satisfies each delivered structural properties to a corresponding required structural property by matching each delivered structural property to a corresponding required structural property.
10. One or more hardware memory devices, not being a signal per se, storing software components useable by one or more computing devices to provide query optimization, the software components comprising: a required properties component for determining required structural properties for physical operators being considered during query optimization, the required structural properties including structural property requirements of inputs to the physical operators, the required structural properties including partitioning properties, grouping properties, and sorting properties, each defining the partition, sort, and group structure, respectively, of input data required from physical operators; a delivered properties component for determining delivered structural properties for the physical operators, the delivered structural properties including structural properties of outputs from the physical operators, the delivered structural properties including partitioning properties, grouping properties, and sorting properties, each defining the partition, sort, and group structure, respectively, of output data delivered from physical operator; and a property matching component for determining whether delivered structural properties satisfy required structural properties to identify one or more valid execution plans, determining whether delivered structural properties satisfy required structural properties, wherein determining whether delivered structural properties satisfy corresponding required structural properties comprises: (a) determining whether delivered partitioning properties satisfy required partitioning properties; (b) determining whether delivered sorting properties satisfy required sorting properties; and (c) determining whether delivered grouping properties satisfy required grouping properties.