MaxCompute:ARG_MAX

Usage notes

• MaxCompute V2.0 provides additional functions. If the functions that you use involve new data types, including TINYINT, SMALLINT, INT, FLOAT, VARCHAR, TIMESTAMP, and BINARY, you must execute a statement to enable the MaxCompute V2.0 data type edition:

  • Session level: Add set odps.sql.type.system.odps2=true; before the SQL statement that you want to execute, and commit and execute them together.

  • Project level: The project owner can enable the MaxCompute V2.0 data type edition for the project based on the project requirements. Statement:

    setproject odps.sql.type.system.odps2=true;

    The configuration takes effect after 10 to 15 minutes.

    For more information about setproject, see Project operations. For more information about the precautions that you must take when you enable the MaxCompute V2.0 data type edition at the project level, see Data type editions.

• If you use an SQL statement that includes multiple aggregate functions and the project resources are insufficient, memory overflow may occur. We recommend that you optimize the SQL statement or purchase computing resources based on your business requirements.

Syntax

arg_max(<valueToMaximize>, <valueToReturn>)

Parameters

• valueToMaximize: required. A value of any data type.

• valueToReturn: required. A value of any data type.

Return value

The return value type is the same as the valueToReturn type. If multiple rows have the maximum value, a value from one of these rows is randomly returned. When the valueToMaximize value is NULL, the row is not included in the calculation.

Sample data

create table if not exists emp
   (empno bigint,
    ename string,
    job string,
    mgr bigint,
    hiredate datetime,
    sal bigint,
    comm bigint,
    deptno bigint);
tunnel upload emp.txt emp; -- Replace emp.txt with the actual path (path and name) to which you upload the data file.

7369,SMITH,CLERK,7902,1980-12-17 00:00:00,800,,20
7499,ALLEN,SALESMAN,7698,1981-02-20 00:00:00,1600,300,30
7521,WARD,SALESMAN,7698,1981-02-22 00:00:00,1250,500,30
7566,JONES,MANAGER,7839,1981-04-02 00:00:00,2975,,20
7654,MARTIN,SALESMAN,7698,1981-09-28 00:00:00,1250,1400,30
7698,BLAKE,MANAGER,7839,1981-05-01 00:00:00,2850,,30
7782,CLARK,MANAGER,7839,1981-06-09 00:00:00,2450,,10
7788,SCOTT,ANALYST,7566,1987-04-19 00:00:00,3000,,20
7839,KING,PRESIDENT,,1981-11-17 00:00:00,5000,,10
7844,TURNER,SALESMAN,7698,1981-09-08 00:00:00,1500,0,30
7876,ADAMS,CLERK,7788,1987-05-23 00:00:00,1100,,20
7900,JAMES,CLERK,7698,1981-12-03 00:00:00,950,,30
7902,FORD,ANALYST,7566,1981-12-03 00:00:00,3000,,20
7934,MILLER,CLERK,7782,1982-01-23 00:00:00,1300,,10
7948,JACCKA,CLERK,7782,1981-04-12 00:00:00,5000,,10
7956,WELAN,CLERK,7649,1982-07-20 00:00:00,2450,,10
7956,TEBAGE,CLERK,7748,1982-12-30 00:00:00,1300,,10

Examples

• Example 1: Return the name of the employee with the highest salary. Sample statement:

  select arg_max(sal, ename) from emp;

  The following result is returned:

  +------------+
  | _c0        |
  +------------+
  | KING       |
  +------------+

• Example 2: Use this function with GROUP BY to group all employees by department (deptno) and return the name of the employee with the highest salary in each group. Sample statement:

  select deptno, arg_max(sal, ename) from emp group by deptno;

  The following result is returned:

  +------------+------------+
  | deptno     | _c1        |
  +------------+------------+
  | 10         | KING       |
  | 20         | SCOTT      |
  | 30         | BLAKE      |
  +------------+------------+

Related functions

ARG_MAX is an aggregate function. For more information about the functions that are used to calculate the average value of multiple input records and to aggregate parameters, see Aggregate functions.