* No need to calculate the new Dn.
*/
String parentId = getParentId( oldId );
// Get the old parentIdAndRdn to get the nb of children and descendant
ParentIdAndRdn parentIdAndRdn = rdnIdx.reverseLookup( oldId );
// Now we can drop it
rdnIdx.drop( oldId );
// Update the descendants
parentIdAndRdn.setParentId( parentId );
parentIdAndRdn.setRdns( newRdn );
rdnIdx.add( parentIdAndRdn, oldId );
entryDnCache.clear();