presto-orc/src/main/java/io/prestosql/orc/DictionaryCompressionOptimizer.java/DictionaryColumnManager/reset
class DictionaryColumnManager:        void reset()
        {
            directEncoded = false;

            pastValueCount = 0;
            pastDictionaryEntries = 0;

            pendingPastValueCount = 0;
            pendingPastDictionaryEntries = 0;
        }