Various techniques are described for improving the performance of a
shared-nothing database system in which at least two of the nodes that
are running the shared-nothing database system have shared access to a
disk. Specifically, techniques are provided for changing the ownership of
data in a shared-nothing database without changing the location of the
data on persistent storage. Because the persistent storage location for
the data is not changed during a transfer of ownership of the data,
ownership can be transferred more freely and with less of a performance
penalty than would otherwise be incurred by a physical relocation of the
data. Various techniques are also described for providing fast run-time
reassignment of ownership. Because the reassignment can be performed
during run-time, the shared-nothing system does not have to be taken
offline to perform the reassignment. Further, the techniques describe how
the reassignment can be performed with relatively fine granularity,
avoiding the need to perform bulk reassignment of large amounts of data
across all nodes merely to reassign ownership of a few data items on one
of the nodes.