Window functions - Amazon OpenSearch Service

Window functions

Note

To see which AWS data source integrations support this SQL command, see Supported OpenSearch SQL commands and functions.

Window functions operate on a group of rows, referred to as a window, and calculate a return value for each row based on the group of rows. Window functions are useful for processing tasks such as calculating a moving average, computing a cumulative statistic, or accessing the value of rows given the relative position of the current row.

Syntax 

window_function [ nulls_option ] OVER ( [ { PARTITION | DISTRIBUTE } BY partition_col_name = partition_col_val ( [ , ... ] ) ] { ORDER | SORT } BY expression [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [ , ... ] [ window_frame ] )

Parameters

  • Ranking functions

    Syntax: RANK | DENSE_RANK | PERCENT_RANK | NTILE | ROW_NUMBER

    Analytic functions

    Syntax: CUME_DIST | LAG | LEAD | NTH_VALUE | FIRST_VALUE | LAST_VALUE

    Aggregate functions

    Syntax: MAX | MIN | COUNT | SUM | AVG | ...

  • nulls_option - Specifies whether or not to skip null values when evaluating the window function. RESPECT NULLS means not skipping null values, while IGNORE NULLS means skipping. If not specified, the default is RESPECT NULLS.

    Syntax: { IGNORE | RESPECT } NULLS

    Note: Only LAG | LEAD | NTH_VALUE | FIRST_VALUE | LAST_VALUE can be used with IGNORE NULLS.

  • window_frame - Specifies which row to start the window on and where to end it.

    Syntax: { RANGE | ROWS } { frame_start | BETWEEN frame_start AND frame_end }

    frame_start and frame_end have the following syntax:

    Syntax: UNBOUNDED PRECEDING | offset PRECEDING | CURRENT ROW | offset FOLLOWING | UNBOUNDED FOLLOWING

    offset: specifies the offset from the position of the current row.

    Note If frame_end is omitted, it defaults to CURRENT ROW.

Examples

CREATE TABLE employees (name STRING, dept STRING, salary INT, age INT);
INSERT INTO employees VALUES ("Lisa", "Sales", 10000, 35);
INSERT INTO employees VALUES ("Evan", "Sales", 32000, 38);
INSERT INTO employees VALUES ("Fred", "Engineering", 21000, 28);
INSERT INTO employees VALUES ("Alex", "Sales", 30000, 33);
INSERT INTO employees VALUES ("Tom", "Engineering", 23000, 33);
INSERT INTO employees VALUES ("Jane", "Marketing", 29000, 28);
INSERT INTO employees VALUES ("Jeff", "Marketing", 35000, 38);
INSERT INTO employees VALUES ("Paul", "Engineering", 29000, 23);
INSERT INTO employees VALUES ("Chloe", "Engineering", 23000, 25);
SELECT * FROM employees;
+-----+-----------+------+-----+
| name|       dept|salary|  age|
+-----+-----------+------+-----+
|Chloe|Engineering| 23000|   25|
| Fred|Engineering| 21000|   28|
| Paul|Engineering| 29000|   23|
|Helen|  Marketing| 29000|   40|
|  Tom|Engineering| 23000|   33|
| Jane|  Marketing| 29000|   28|
| Jeff|  Marketing| 35000|   38|
| Evan|      Sales| 32000|   38|
| Lisa|      Sales| 10000|   35|
| Alex|      Sales| 30000|   33|
+-----+-----------+------+-----+
SELECT name, dept, salary, RANK() OVER (PARTITION BY dept ORDER BY salary) AS rank FROM employees;
+-----+-----------+------+----+
| name|       dept|salary|rank|
+-----+-----------+------+----+
| Lisa|      Sales| 10000|   1|
| Alex|      Sales| 30000|   2|
| Evan|      Sales| 32000|   3|
| Fred|Engineering| 21000|   1|
|  Tom|Engineering| 23000|   2|
|Chloe|Engineering| 23000|   2|
| Paul|Engineering| 29000|   4|
|Helen|  Marketing| 29000|   1|
| Jane|  Marketing| 29000|   1|
| Jeff|  Marketing| 35000|   3|
+-----+-----------+------+----+
SELECT name, dept, salary, DENSE_RANK() OVER (PARTITION BY dept ORDER BY salary ROWS BETWEEN
UNBOUNDED PRECEDING AND CURRENT ROW) AS dense_rank FROM employees;
+-----+-----------+------+----------+
| name|       dept|salary|dense_rank|
+-----+-----------+------+----------+
| Lisa|      Sales| 10000|         1|
| Alex|      Sales| 30000|         2|
| Evan|      Sales| 32000|         3|
| Fred|Engineering| 21000|         1|
|  Tom|Engineering| 23000|         2|
|Chloe|Engineering| 23000|         2|
| Paul|Engineering| 29000|         3|
|Helen|  Marketing| 29000|         1|
| Jane|  Marketing| 29000|         1|
| Jeff|  Marketing| 35000|         2|
+-----+-----------+------+----------+
SELECT name, dept, age, CUME_DIST() OVER (PARTITION BY dept ORDER BY age
RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS cume_dist FROM employees;
+-----+-----------+------+------------------+
| name|       dept|age   |         cume_dist|
+-----+-----------+------+------------------+
| Alex|      Sales|    33|0.3333333333333333|
| Lisa|      Sales|    35|0.6666666666666666|
| Evan|      Sales|    38|               1.0|
| Paul|Engineering|    23|              0.25|
|Chloe|Engineering|    25|              0.75|
| Fred|Engineering|    28|              0.25|
|  Tom|Engineering|    33|               1.0|
| Jane|  Marketing|    28|0.3333333333333333|
| Jeff|  Marketing|    38|0.6666666666666666|
|Helen|  Marketing|    40|               1.0|
+-----+-----------+------+------------------+
SELECT name, dept, salary, MIN(salary) OVER (PARTITION BY dept ORDER BY salary) AS min
FROM employees;
+-----+-----------+------+-----+
| name|       dept|salary|  min|
+-----+-----------+------+-----+
| Lisa|      Sales| 10000|10000|
| Alex|      Sales| 30000|10000|
| Evan|      Sales| 32000|10000|
|Helen|  Marketing| 29000|29000|
| Jane|  Marketing| 29000|29000|
| Jeff|  Marketing| 35000|29000|
| Fred|Engineering| 21000|21000|
|  Tom|Engineering| 23000|21000|
|Chloe|Engineering| 23000|21000|
| Paul|Engineering| 29000|21000|
+-----+-----------+------+-----+
SELECT name, salary,
LAG(salary) OVER (PARTITION BY dept ORDER BY salary) AS lag,
LEAD(salary, 1, 0) OVER (PARTITION BY dept ORDER BY salary) AS lead
FROM employees;
+-----+-----------+------+-----+-----+
| name|       dept|salary|  lag| lead|
+-----+-----------+------+-----+-----+
| Lisa|      Sales| 10000|NULL |30000|
| Alex|      Sales| 30000|10000|32000|
| Evan|      Sales| 32000|30000|    0|
| Fred|Engineering| 21000| NULL|23000|
|Chloe|Engineering| 23000|21000|23000|
|  Tom|Engineering| 23000|23000|29000|
| Paul|Engineering| 29000|23000|    0|
|Helen|  Marketing| 29000| NULL|29000|
| Jane|  Marketing| 29000|29000|35000|
| Jeff|  Marketing| 35000|29000|    0|
+-----+-----------+------+-----+-----+
SELECT id, v,
LEAD(v, 0) IGNORE NULLS OVER w lead,
LAG(v, 0) IGNORE NULLS OVER w lag,
NTH_VALUE(v, 2) IGNORE NULLS OVER w nth_value,
FIRST_VALUE(v) IGNORE NULLS OVER w first_value,
LAST_VALUE(v) IGNORE NULLS OVER w last_value
FROM test_ignore_null
WINDOW w AS (ORDER BY id)
ORDER BY id;
+--+----+----+----+---------+-----------+----------+
|id|   v|lead| lag|nth_value|first_value|last_value|
+--+----+----+----+---------+-----------+----------+
| 0|NULL|NULL|NULL|     NULL|       NULL|      NULL|
| 1|   x|   x|   x|     NULL|          x|         x|
| 2|NULL|NULL|NULL|     NULL|          x|         x|
| 3|NULL|NULL|NULL|     NULL|          x|         x|
| 4|   y|   y|   y|        y|          x|         y|
| 5|NULL|NULL|NULL|        y|          x|         y|
| 6|   z|   z|   z|        y|          x|         z|
| 7|   v|   v|   v|        y|          x|         v|
| 8|NULL|NULL|NULL|        y|          x|         v|
+--+----+----+----+---------+-----------+----------+