[SPARK-31452][SQL] Do not create partition spec for 0-size partitions in AQE #28226
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cloud-fan
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Apr 15, 2020
sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/OptimizeSkewedJoin.scala
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dongjoon-hyun
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Test build #121330 has finished for PR 28226 at commit
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| // and the partitions length is 2 * numMappers = 4 | ||
| assert(localShuffleRDD1.getPartitions.length == 4) | ||
| // math.max(1, advisoryParallelism / numMappers): math.max(1, 3/2) = 1 | ||
| // and the partitions length is 2 * numMappers = 2 |
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2 * numMappers = 2 -> 1 * numMappers = 2?
| // Partition 4: only left side is skewed, and divide into 2 splits, so | ||
| // 2 sub-partitions. | ||
| // So total (8 + 1 + 3) partitions. | ||
| // So total (8 + 0 + 3) partitions. |
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The original statement was wrong: 8 + 1 + 3 -> 8 + 1 + 2.
So, the new statement should be 8 + 0 + 2 instead of 8 + 0 + 3.
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Hi, @cloud-fan . The new logic looks good to me. I left only two minor comments. |
maryannxue
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Apr 16, 2020
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LGTM |
Ngone51
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Apr 20, 2020
sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/OptimizeSkewedJoin.scala
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Test build #121505 has finished for PR 28226 at commit
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dongjoon-hyun
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Apr 20, 2020
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+1, LGTM. Thank you, @cloud-fan and all.
Merged to master.
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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What changes were proposed in this pull request?
This PR skips creating the partition specs in
ShufflePartitionsUtilfor 0-size partitions, which avoids launching unnecessary tasks that do nothing.Why are the changes needed?
launching tasks that do nothing is a waste.
Does this PR introduce any user-facing change?
no
How was this patch tested?
updated tests