@Override
public RandomAccessDocIdSet getRandomAccessDocIdSet(final BoboIndexReader reader) throws IOException {
final FacetDataCache dataCache = facetDataCacheBuilder.build(reader);
final OpenBitSet openBitSet = getBitSet(dataCache);
long count = openBitSet.cardinality();
if (count == 0) {
return EmptyDocIdSet.getInstance();
} else {
final boolean multi = dataCache instanceof MultiValueFacetDataCache;
final MultiValueFacetDataCache multiCache = multi ? (MultiValueFacetDataCache) dataCache : null;