MySQL Window Functions or Analytic Functions

MySQL 8.0.2 introduces SQL window functions, or analytic functions as they are also sometimes called. They join CTEs (available since 8.0.1) as two of our most requested features, and are long awaited and powerful features. This is the first of a series of posts describing the details. Let’s get started!



Similar to grouped aggregate functions, window functions perform some calculation on a set of rows, e.g. COUNT or SUM. But where a grouped aggregate collapses this set of rows into a single row, a window function will perform the aggregation for each row in the result set, letting each row retain its identity:

Given this simple table, notice the difference between the two SELECTs:

mysql> CREATE TABLE t(i INT);
mysql> INSERT INTO t VALUES (1),(2),(3),(4);

mysql> SELECT SUM(i) AS sum FROM t;
| sum |
| 10 |

mysql> SELECT i, SUM(i) OVER () AS sum FROM t;
| i | sum |
| 1 | 10 |
| 2 | 10 |
| 3 | 10 |
| 4 | 10 |


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