Internally we have a little tool that will do a rough estimate of how many rows there are in a dataHbase. It keeps getting larger and larger partitions running scanners until it turns up > N occupied rows. Once it has a number > N, it multiples by the partition size to get an approximate row count.
This issue is about generalizing this feature so it could sit in the general hbase install. It would look something like:
Larger minimumCountPerPartition and maximumPartitionSize values would make the count more accurate but would mean the method ran longer.