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We will provide an experimental configuration named “table.optimizer.window-rewrite-enabled” to allow users to fall back to the behavior of the previous version. In the long term, the GroupWindowAggregate node will be removed once the WindowAggregate node can align with all the capabilities of the GroupWindowAggregate node. This part of the removal work should be entirely internal to the code, and does not need to be perceived by users.

Note that if the input schema also includes a regular column named "window_start", the rewriting will result in a conflict with the additional column 'window_start' produced by Window TVF. For more details, please refer to FLINK-25499[6]. To address this issue, we will introduce a configuration option named "table.window-additional-columns.prefix" that allows users to provide a special prefix for the three columns generated by the window TVF.

Compatibility, Deprecation, and Migration Plan

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