presto-orc/src/main/java/io/prestosql/orc/writer/DictionaryBuilder.java/DictionaryBuilder/calculateMaxFill
class DictionaryBuilder:    private static int calculateMaxFill(int hashSize)
    {
        int maxFill = (int) Math.ceil(hashSize * FILL_RATIO);
        if (maxFill == hashSize) {
            maxFill--;
        }
        return maxFill;
    }