static boolean canCreateSargFromConf(Configuration conf) {
    if (getNeededColumnNamesString(conf) == null) {
      LOG.debug("No ORC pushdown predicate - no column names");
      return false;
    }
    if (!ConvertAstToSearchArg.canCreateFromConf(conf)) {
      LOG.debug("No ORC pushdown predicate");
      return false;
    }
    return true;
  }
Take the configuration and figure out which columns we need to include.
@param readerSchema the types for the reader
@param conf the configuration
ql/src/java/org/apache/hadoop/hive/ql/io/orc/OrcInputFormat.java