public void writeToOutputStream(DataOutputStream out) throws IOException {
        out.writeInt(dictionary.size());
        for (LongObjectPair<Entry> pair : dictionary.keyValuesView()) {
            out.writeLong(pair.getOne());
            Entry entry = pair.getTwo();
            SerializationHelper.writeIntArray(entry.docIds, out);
            SerializationHelper.writeIntArray(entry.dataRefs, out);
        }
    }
Retrieves a posting list for a given key

@param key the key to lookup
@return list of postings
predicate-search/src/main/java/com/yahoo/search/predicate/index/SimpleIndex.java