Currently, RowCounter only allows a single key range to be used as a filter. It would be useful in some cases to be able to specify multiple key ranges (or prefixes) in the same job. (For example, counting over a set of Phoenix tenant ids in an unsalted table)
This could be done by enhancing the existing key range parameter to take multiple start/stop row pairs. Alternately, a new --row-prefixes option could be added, similar to what
HBASE-15847 did for VerifyReplication.