illiabarbashov-sketch opened a new pull request, #6456:
URL: https://github.com/apache/hive/pull/6456
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### What changes were proposed in this pull request?
1. New Hive configurations: hive.merge.join.skew.threshold and
hive.merge.join.skew.abort
2. A new SkewedMergeJoinMonitor class to manage those configurations and log
skew join event or abort it.
3. Unit tests to cover positive and negative cases
4. Query tests to cover clientpositive and clientnegative test cases
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### Why are the changes needed?
1. This feature adds observability to merge join operator and flags the
skewed keys
3. Clients have problem with Skewed Merge Join when the job is stuck and
there are no progress and no information about the reasons behind this issue.
This feature adds a configuration to abort the stuck job if the threshold is
hit.
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### Does this PR introduce _any_ user-facing change?
No
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### How was this patch tested?
- Unit tests
- Query tests with clientpositive and clientnegative cases
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