viirya opened a new pull request #28846:
URL: https://github.com/apache/spark/pull/28846
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### What changes were proposed in this pull request?
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This patch changes the current way of creating query stages in AQE. Instead
of creating query stages in batch, incrementally creating query stage can bring
the optimization in earlier. It could avoid unnecessary local shuffle.
### Why are the changes needed?
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The current way of creating query stage in AQE is in batch. For example, the
children of a sort merge join will be materialized as query stages in a batch.
Then AQE brings the optimization in and optimize sort merge join to broadcast
join. Except for the broadcasted exchange, we don't need do any exchange on
another side of join but we already materialized the exchange. Currently AQE
wraps the materialized exchange with local reader, but it still brings
unnecessary I/O. We can avoid unnecessary local shuffle by incrementally
creating query stage.
### Does this PR introduce _any_ user-facing change?
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No
### How was this patch tested?
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Unit tests.
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