  We study the constraint structure of Fierz -Pauli action in both flat and
curved space in the framework of Hamiltonian formalism. We observe an abrupt
change in the constraint algebra and the characteristics of the constraints
when the mass term is turned off. As is well-known, for de Sitter background
with a special tuning of the mass, we will have a gauge symmetry and one degree
of freedom less. We will show how this abrupt change in the behavior of the
system is reflected on the properties of the constraint algebra. We also obtain
the generating functional of gauge transformations both for the massless and
partially massless theories.
