public AcidOperationalProperties setInsertOnly(boolean isInsertOnly) {
      return set(isInsertOnly, INSERT_ONLY_BIT);
    }
Sets the hash-based merge property for ACID operations that combines delta files using
GRACE hash join based approach, when turned on. (Currently unimplemented!)
@param isHashBasedMerge a boolean property that turns on hash-based merge when true.
@return the acidOperationalProperties object.
ql/src/java/org/apache/hadoop/hive/ql/io/AcidUtils.java