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https://issues.apache.org/jira/browse/SPARK-35961?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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XiDuo You updated SPARK-35961:
------------------------------
Description:
After [SPARK-35725](https://issues.apache.org/jira/browse/SPARK-35725), we
might expand partition if that partition is skewed. So the partition number
check `bytesByPartitionId.length == partitionSpecs.size` would be wrong if some
partitions are coalesced and some partitions are splitted into smaller.
Note that, it's unlikely happened in real world since it used RoundRobin.
Otherhand, after
[SPARK-34899](https://issues.apache.org/jira/browse/SPARK-34899), we use origin
plan if can not coalesce partitions. So the assuming of that shuffle stage has
`CustomShuffleReaderExec` with no effect is always false in
`REBALANCE_PARTITIONS_BY_NONE` shuffle origin. That said, if no rule was
efficient, there would be no `CustomShuffleReaderExec`.
was:
After [SPARK-35725](https://issues.apache.org/jira/browse/SPARK-35725), we
might expand partition if that partition is skewed. So the partition number
check `bytesByPartitionId.length == partitionSpecs.size` would be wrong if some
partitions are coalesced and some partitions
are splitted into smaller (it's unlikely in real world since it used
RoundRobin).
Otherhand, after
[SPARK-34899](https://issues.apache.org/jira/browse/SPARK-34899), we use origin
plan if can not coalesce partitions. So the assuming of that shuffle stage has
`CustomShuffleReaderExec` with no effect is always false. That said, if no rule
is efficient, there would be no `CustomShuffleReaderExec`.
> Only use local shuffle reader for REBALANCE_PARTITIONS_BY_NONE without
> CustomShuffleReaderExec
> ----------------------------------------------------------------------------------------------
>
> Key: SPARK-35961
> URL: https://issues.apache.org/jira/browse/SPARK-35961
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 3.2.0
> Reporter: XiDuo You
> Priority: Major
>
> After [SPARK-35725](https://issues.apache.org/jira/browse/SPARK-35725), we
> might expand partition if that partition is skewed. So the partition number
> check `bytesByPartitionId.length == partitionSpecs.size` would be wrong if
> some partitions are coalesced and some partitions are splitted into smaller.
> Note that, it's unlikely happened in real world since it used RoundRobin.
> Otherhand, after
> [SPARK-34899](https://issues.apache.org/jira/browse/SPARK-34899), we use
> origin plan if can not coalesce partitions. So the assuming of that shuffle
> stage has `CustomShuffleReaderExec` with no effect is always false in
> `REBALANCE_PARTITIONS_BY_NONE` shuffle origin. That said, if no rule was
> efficient, there would be no `CustomShuffleReaderExec`.
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