There is a performance difference. You have an upper bound of returning all
data to the client be scanned, even with a FirstEntryInRowIterator. Imagine
a table layout where each Key/Value pair represents a single row or
document. Using a counting iterator will return a count (most likely a
64-bit long) for each tablet, that the client can then add together.

There is a deleteRows feature (TableOperations#deleteRows) which may be
what you want. It avoids having to bring data back to the client.

On Thu, Nov 12, 2015 at 9:23 AM, z11373 <[EMAIL PROTECTED]> wrote: