beyond1920 edited a comment on pull request #16215:
URL: https://github.com/apache/flink/pull/16215#issuecomment-868182128
@wenlong88 Window offset has no effect on watermark. Whether it would effect
time attribute depends on each window operator. For window aggregate, time
attribute is (window_end - 1). window_end would be shifted if set window offset.
For example, if user needs to calculate PV every 1 hour, but wanna window
begin at 05:00 instead of 00:00 of each hour.
The sql is as following. window offset is 5 minute, it would not effect on
watermark, rowtime attribute would be at YYYY-MM-DD hh:04:59.999Z instead of
YYYY-MM-DD hh-1:59:59.999Z.
`
SELECT
`product`,
window_start,
window_end,
COUNT(`user`) AS pv
FROM TABLE(
TUMBLE(TABLE temp_table, DESCRIPTOR(rowtime), INTERVAL '1' HOUR,
INTERVAL '5' MINUTE))
GROUP BY product, window_start, window_end
`
I add a cascaded window aggregate with window offset in
`WindowAggregateITCase#testCascadeEventTimeTumbleWindowWithOffset`, please have
a look.
Thanks a lot.
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