public static void setAcidVersionInDataFile(Writer writer) {
      //so that we know which version wrote the file
      writer.addUserMetadata(ACID_VERSION_KEY, UTF8.encode(String.valueOf(ORC_ACID_VERSION)));
    }
Include current acid version in file footer.
@param writer - file written
ql/src/java/org/apache/hadoop/hive/ql/io/AcidUtils.java