Regarding ambulkdelete, amvacuumcleanup index methods

[Abinaya k]

Hai all,
      We are building In-memory index extension for postgres. We would
capture table inserts, updates, deletes using triggers. During vacuum
operation, postgres would give calls to ambulkdelete, amvacuumcleanup (as
part of index cleanup). As we handle all updates, deletes using triggers,
we don't have to do any index cleanup in ambulkdelete. But, what stats
should i return from ambulkdelete and amvacuumcleanup? Is that necessary to
return stats from ambulkdelete and amvacuumcleanup ?