Updating HDFStore in place
Currently I use the HDF5 interface to store timeseries and it works great for selection.  However, the only way I see to update them is to select the existing stored timeseries and then merge the update with the existing data.  This can obviously be expensive if the existing series is large.  Is it possible to update a store by just passing in the new data?  If so, is there an example somewhere?
