presto-orc/src/main/java/io/prestosql/orc/DictionaryCompressionOptimizer.java/DictionaryColumnManager/updateHistory
class DictionaryColumnManager:        public void updateHistory(int rowCount)
        {
            this.rowCount = rowCount;
            long currentValueCount = dictionaryColumn.getValueCount();
            if (currentValueCount - pendingPastValueCount >= 1024) {
                pastValueCount = pendingPastValueCount;
                pastDictionaryEntries = pendingPastDictionaryEntries;

                pendingPastValueCount = currentValueCount;
                pendingPastDictionaryEntries = dictionaryColumn.getDictionaryEntries();
            }
        }