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From Manu Zhang <owenzhang1...@gmail.com>
Subject watermark trigger doesn't check whether element's timestamp is passed
Date Mon, 24 Oct 2016 04:30:24 GMT

Say I have a window state of List(("a", 1:00), ("b", 1:03), ("c", 1:06))
which is triggered to emit when watermark passes the timestamp of an
element. For example,

on watermark(1:01), List(("a", 1:00)) is emitted
on watermark(1:04), List(("a", 1:00), ("b", 1:03)) is emitted
on watermark(1:07), List(("a", 1:00), ("b", 1:03), ("c", 1:06)) is emitted

It seems that if *("c", 1:06) is processed before watermark(1:04)*
List(("a", 1:00), ("b", 1:03), ("c", 1:06)) will be emitted on
watermark(1:04). This is incorrect since there could be elements with
timestamp between 1:04 and 1:06 that have not arrived yet.

I guess this is because watermark trigger doesn't check whether element's
timestamp has been passed.

Please correct me if any of the above is not right.

Manu Zhang

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