tuple in the present example other possibilities include appending a flag to the data item or modifying a value within meta data associated with the data item fig6 shows an example of a deletion operation that is intended to delete the item inserted in fig5 the deletion procedure is highly analagous to the insertion procedure a client connects to the only node of rank zero and requests deletion of the tuple 5 6 0 this is accomplished by inserting the corresponding anti tuple 5 6 1 the coverage values shown have been altered from fig5 to reflect the inclusion of the additional key within the key list similarly the tuple inserted in fig5 is assumed to have been of the form 5 6 0 the insertion of the anti tuple proceeds as the insertion of the tuple in fig5 thus the anti tuple 5 6 1 arrives for storage at nodes nb and nc arrival of the anti tuple at the same location as the tuple results in deletion of the tuple as noted above deletion may entail the actual removal of the tuple from storage which may be performed in several ways most simply upon storage of an anti tuple the storing node checks for the presence of the corresponding tuple if the corresponding tuple is present it is removed from storage alternatively the anti tuple may be stored alongside the tuple and optionally removed at a later time through a garbage collection process in this approach or in another alternative approach in which the tuple is stored indefinitely the presence of the anti tuple alongside the tuple results in the exclusion of the tuple from any subsequent data retrieval operations finally the specification of an anti tuple may also allow for a wild card.