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Re:Chronon, Airbnb's ML Feature Platform, Is Now Open Source by better365 on Thursday April 11, 2024 @01:50PM (#40004858)
That's fair.

Actually, Last is usually called last_k(n), so that you can specify the number of the values in the result array. For example, if the input column is page_view_id and n = 300, it will return the last 300 page_view_id as an array. If a window is used, for example, 7d, it will truncate the results to the past 7d. The LAST_VALUE() seems to return the last value from an ordered set. Hope that helps. Thanks for your interests.

Re:Chronon, Airbnb's ML Feature Platform, Is Now Open Source by mulmen on Thursday April 11, 2024 @03:04PM (#40005631)
In SQL we do that with a RANK window function then apply a filter to that rank. It can also be done with a correlated subquery.