Comment by rubyorchard

Great point and looking forward to Lua support in 2.6. GETRANGE and SETRANGE operations also allow buffered writes at the collection time because setting bit to 1 is an idempotent operation. They are particularly attractive in sharded environment where one can perform:

  WATCH
  bits = GETRANGE ...
  bits = bits | buffered_bits
  MULTI
  SETRANGE .... bits
  EXEC