[SPARK-32083][SQL][3.0] AQE should not coalesce partitions for SinglePartition #29321
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viirya
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Jul 31, 2020
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Could you resolve the conflict, @cloud-fan ? |
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Test build #126892 has finished for PR 29321 at commit
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This PR updates the AQE framework to at least return one partition during coalescing. This PR also updates `ShuffleExchangeExec.canChangeNumPartitions` to not coalesce for `SinglePartition`. It's a bit risky to return 0 partitions, as sometimes it's different from empty data. For example, global aggregate will return one result row even if the input table is empty. If there is 0 partition, no task will be run and no result will be returned. More specifically, the global aggregate requires `AllTuples` and we can't coalesce to 0 partitions. This is not a real bug for now. The global aggregate will be planned as partial and final physical agg nodes. The partial agg will return at least one row, so that the shuffle still have data. But it's better to fix this issue to avoid potential bugs in the future. According to apache#28916, this change also fix some perf problems. no updated test. Closes apache#29307 from cloud-fan/aqe. Authored-by: Wenchen Fan <[email protected]> Signed-off-by: Wenchen Fan <[email protected]>
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cloud-fan
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Test build #126948 has finished for PR 29321 at commit
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retest this please |
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Test build #126967 has finished for PR 29321 at commit
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merged to 3.0 |
cloud-fan
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Aug 3, 2020
…Partition This is a partial backport of #29307 Most of the changes are not needed because #28226 is in master only. This PR only backports the safeguard in `ShuffleExchangeExec.canChangeNumPartitions` Closes #29321 from cloud-fan/aqe. Authored-by: Wenchen Fan <[email protected]> Signed-off-by: Wenchen Fan <[email protected]>
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This is a partial backport of #29307
Most of the changes are not needed because #28226 is in master only.
This PR only backports the safeguard in
ShuffleExchangeExec.canChangeNumPartitions