1. A computer-implemented method of partition pruning, comprising: receiving a query that requests retrieval of data items from a partitioned object; identifying a plurality of conditions specified in a predicate of the query, wherein the plurality of conditions includes a first condition and a second condition, wherein the first condition and the second condition are combined using an OR operation; based on the plurality of conditions, determining a non-contiguous set of not-pruned partitions; and during execution of the query, only accessing data items in partitions of said partitioned object that reside in partitions that are members of said non-contiguous set of not-pruned partitions; wherein the method is performed by one or more computing devices.