17. A computer program product comprising a tangible computer readable storage medium including a computer readable program, wherein the computer readable program when executed by a processor on a computer causes the computer to perform: in response to receiving a new document, generating an assigned-doc-ID for the new document; identifying, for the assigned-doc-ID, a virtual-index-epoch from a virtual-index-epoch map that includes virtual-index-epochs that are each assigned a range of assign-doc-IDs; applying a first function to a virtual-index-epoch value of the identified virtual-index-epoch to identify a logical partition; applying a second function to the identified logical partition to identify a physical partition; and placing the new document into the identified physical partition associated with the identified virtual-index-epoch.
17. A computer program product comprising a tangible computer readable storage medium including a computer readable program, wherein the computer readable program when executed by a processor on a computer causes the computer to perform: in response to receiving a new document, generating an assigned-doc-ID for the new document; identifying, for the assigned-doc-ID, a virtual-index-epoch from a virtual-index-epoch map that includes virtual-index-epochs that are each assigned a range of assign-doc-IDs; applying a first function to a virtual-index-epoch value of the identified virtual-index-epoch to identify a logical partition; applying a second function to the identified logical partition to identify a physical partition; and placing the new document into the identified physical partition associated with the identified virtual-index-epoch. 23. The computer program product of claim 17 , wherein the first function and the second function are one of system determined and user specified, wherein the system determined functions are based on one of system capacity, modeled performance of a physical partition, and actual performance of the physical partition.