@Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null) {
      return false;
    }
    if (!(obj instanceof HCatSchema)) {
      return false;
    }
    HCatSchema other = (HCatSchema) obj;
    if (!this.getFields().equals(other.getFields())) {
      return false;
    }
    return true;
  }
Note : The position will be re-numbered when one of the preceding columns are removed.
Hence, the client should not cache this value and expect it to be always valid.
@param fieldName
@return the index of field named fieldName in Schema. If field is not
present, returns null.
hcatalog/core/src/main/java/org/apache/hive/hcatalog/data/schema/HCatSchema.java