presto-hive/src/main/java/io/prestosql/plugin/hive/HiveConfig.java/HiveConfig/getMaxInitialSplitSize
class HiveConfig:    public DataSize getMaxInitialSplitSize()
    {
        if (maxInitialSplitSize == null) {
            return new DataSize(maxSplitSize.getValue() / 2, maxSplitSize.getUnit());
        }
        return maxInitialSplitSize;
    }