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Window Functions

Window functions apply to a subset of rows (a window) relative to the current row for computational purposes. These functions can be applied to the following transforms:

Primary Key:

When window functions are used, each row in the windowed output should be identified by a primary key. This primary key, which identifies unique rows, can be specified in one of the following ways:

  • The Order by field indicates unique row identifiers. This field can contain one or more column references.

  • A combination of Order by andGroup by fields can create a unique identifier for each row.

This primary key requirement applies to window functions used with any supported transform.

注記

Null values are ignored as inputs to these functions.