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. 24. The computer program product of claim 17 , wherein the assigned-doc-ID comprises a non-reusable unique identifier that is a monotonically increasing number of sufficient precision.