RESET WHEN is a Teradata feature used in SQL analytical window functions. It is an extension to the ANSI SQL standard. RESET WHEN determines the partition over which an SQL window function operates based on some specified condition. If the condition evaluates to TRUE, a new, dynamic sub-partition is created inside the existing window partition. For more information about RESET WHEN, see the Teradata documentation.
Amazon Redshift doesn’t support RESET WHEN in SQL window functions. To implement this functionality, you have to convert RESET WHEN to the native SQL syntax in Amazon Redshift, and use multiple, nested functions. This pattern demonstrates how you can use the Teradata RESET WHEN feature and how you can convert it to Amazon Redshift SQL syntax.
