// ??Fast copy by record.
private static void bptCopy(RangeIndex bpt1, RangeIndex bpt2, String label)
{
ProgressLogger monitor = new ProgressLogger(log, label, tickQuantum, superTick) ;
monitor.start() ;
RecordFactory rf = bpt1.getRecordFactory() ;
Iterator<Record> iter1 = bpt1.iterator() ;
long counter = 0 ;
// Use the same slot each time.