public static String stripIdentifierQuotes(String val) {
    if ((val.charAt(0) == '`' && val.charAt(val.length() - 1) == '`')) {
      val = val.substring(1, val.length() - 1);
    }
    return val;
  }
Calculates the partition prefix length based on the drop spec.
This is used to avoid deleting archived partitions with lower level.
For example, if, for A and B key cols, drop spec is A=5, B=6, we shouldn't drop
archived A=5/, because it can contain B-s other than 6.
ql/src/java/org/apache/hadoop/hive/ql/parse/ParseUtils.java