Tumbling Window

A “tumbling window” is a collection of rows that are aggregated to produce a fewer number of output rows, such as “the sum of the last twenty rows” or “the sum of the rows in the last hour”. One row is returned for every group of rows.

As a result, the total number of output rows are limited: many rows in, one row out. Tumbling windows are actually not “windows” in the SQL sense, but rows that are aggregated with SELECT STREAM … GROUP BY - see GROUP BY for more information.