ROW_NUMBER function to calculate the sequence number of a row - MaxCompute

Returns a unique, sequential number for each row within a partition, starting at 1.

Limitations

Window functions are supported only in SELECT statements.
A window function cannot contain nested window functions or nested aggregate functions.
Window functions and aggregate functions of the same level cannot be used together.

Syntax

row_number() over ([partition_clause] [orderby_clause])

frame_clause is not supported.

Usage notes

ROW_NUMBER assigns each row a unique number. No two rows in the same partition share the same value, even when the ORDER BY column contains ties — unlike RANK and DENSE_RANK, which assign the same number to tied rows.

`PARTITION BY`: Divides rows into independent groups before numbering. For example, use PARTITION BY deptno to restart the count at 1 for each department.
`ORDER BY`: Determines the sequence within each partition. For example, use ORDER BY sal DESC to number employees from highest to lowest salary.

For the full window specification, see windowing_definition.

Return value

Returns a value of the BIGINT type.

Examples

The following examples use a table named emp. To create the table and load the sample data, run:

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;

The emp.txt file contains the following data:

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

Rank employees by salary within each department

The following query partitions employees by department and assigns a rank within each partition in descending salary order.

select deptno, ename, sal,
       row_number() over (partition by deptno order by sal desc) as nums
from emp;

Result:

+------------+------------+------------+------------+
| deptno     | ename      | sal        | nums       |
+------------+------------+------------+------------+
| 10         | JACCKA     | 5000       | 1          |
| 10         | KING       | 5000       | 2          |
| 10         | CLARK      | 2450       | 3          |
| 10         | WELAN      | 2450       | 4          |
| 10         | TEBAGE     | 1300       | 5          |
| 10         | MILLER     | 1300       | 6          |
| 20         | SCOTT      | 3000       | 1          |
| 20         | FORD       | 3000       | 2          |
| 20         | JONES      | 2975       | 3          |
| 20         | ADAMS      | 1100       | 4          |
| 20         | SMITH      | 800        | 5          |
| 30         | BLAKE      | 2850       | 1          |
| 30         | ALLEN      | 1600       | 2          |
| 30         | TURNER     | 1500       | 3          |
| 30         | MARTIN     | 1250       | 4          |
| 30         | WARD       | 1250       | 5          |
| 30         | JAMES      | 950        | 6          |
+------------+------------+------------+------------+

In department 10, JACCKA and KING both earn 5000 but receive different row numbers (1 and 2). ROW_NUMBER always assigns unique values — unlike RANK, which would assign both employees rank 1.

What's next

ROW_NUMBER is a window function. For other window functions that sort or rank data, see Window functions.