@Override
 public void collect(int doc, long bucketOrd) {
   visitedOrds = bigArrays.grow(visitedOrds, bucketOrd + 1);
   FixedBitSet bits = visitedOrds.get(bucketOrd);
   if (bits == null) {
     bits = new FixedBitSet(maxOrd);
     visitedOrds.set(bucketOrd, bits);
   }
   values.setDocument(doc);
   final int valueCount = values.cardinality();
   for (int i = 0; i < valueCount; ++i) {
     bits.set((int) values.ordAt(i));
   }
 }