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Posted to user@flink.apache.org by Ahmad Ebrahimi <ea...@gmail.com> on 2022/02/08 19:33:00 UTC

Temporal join unexpected behavior

Hi.

It seems event time temporal join has a bug in version 1.14.3.
the left and right side of the join are inverted.

In the this query:

SELECT * FROM orders AS o
LEFT OUTER JOIN products FOR SYSTEM_TIME AS OF o.updatedAt AS p
ON o.pId = p.id

join triggered when a new event is published to the products table. but i
think join should be triggered when a new event was published in the orders
table.

Please help me if I am wrong.

Thank you.

Re: Temporal join unexpected behavior

Posted by Roman Khachatryan <ro...@apache.org>.

Hi,

According to the documentation, event-time temporal join is triggered
by a watermark from the left and right sides. So the described
behavior seems correct.

[1]
https://nightlies.apache.org/flink/flink-docs-release-1.14/docs/dev/table/sql/queries/joins/#event-time-temporal-join

Regards,
Roman

On Tue, Feb 8, 2022 at 8:33 PM Ahmad Ebrahimi <ea...@gmail.com> wrote:
>
> Hi.
>
> It seems event time temporal join has a bug in version 1.14.3.
> the left and right side of the join are inverted.
>
> In the this query:
>
> SELECT * FROM orders AS o
> LEFT OUTER JOIN products FOR SYSTEM_TIME AS OF o.updatedAt AS p
> ON o.pId = p.id
>
> join triggered when a new event is published to the products table. but i think join should be triggered when a new event was published in the orders table.
>
> Please help me if I am wrong.
>
> Thank you.