Window 関数 - Amazon OpenSearch サービス

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Window 関数

注記

このSQLコマンドをサポートする AWS データソース統合を確認するには、「」を参照してくださいサポートされている OpenSearch SQLコマンドと関数。

ウィンドウ関数は、ウィンドウと呼ばれる行のグループで動作し、行のグループに基づいて各行の戻り値を計算します。ウィンドウ関数は、移動平均の計算、累積統計の計算、現在の行の相対的な位置を与えられた行の値へのアクセスなどのタスクの処理に役立ちます。

[Syntax] (構文) 

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 ] )

パラメータ

  • ランク付け関数

    構文: RANK | DENSE_RANK | PERCENT_RANK | NTILE | ROW_NUMBER

    分析関数

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

    集計関数

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

  • nulls_option - ウィンドウ関数を評価するときに null 値をスキップするかどうかを指定します。 RESPECTNULLSは null 値をスキップしないことを意味しますが、 はスキップIGNORENULLSを意味します。指定しない場合、デフォルトは RESPECT ですNULLS。

    構文: { IGNORE | RESPECT } NULLS

    注: Only LAG | LEAD | NTH_VALUE | FIRST_VALUE | | は でLAST_VALUE使用できますIGNORE NULLS。

  • window_frame - ウィンドウを開始する行とウィンドウを終了する場所を指定します。

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

    frame_start と frame_end の構文は次のとおりです。

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

    offset: 現在の行の位置からのオフセットを指定します。

    注: frame_end を省略すると、デフォルトで CURRENT になりますROW。

例

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|
+--+----+----+----+---------+-----------+----------+