public static String qualifyFunctionName(String functionName, String dbName) {
    if (isQualifiedFunctionName(functionName)) {
      return functionName;
    }
    return dbName + "." + functionName;
  }
Extracts the UDAFE evaluators of the specified class from the provided aggregations.
ql/src/java/org/apache/hadoop/hive/ql/exec/FunctionUtils.java