zabetak commented on a change in pull request #1325:
URL: https://github.com/apache/hive/pull/1325#discussion_r466421484
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File path:
ql/src/test/results/clientpositive/llap/dynamic_semijoin_reduction_2.q.out
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@@ -79,27 +79,25 @@ STAGE PLANS:
Tez
#### A masked pattern was here ####
Edges:
Review comment:
The plan in `dynamic_semijoin_reduction_2.q` has three single column
semijoin reducers that get merged to one multi column one. As a result three
reducers get merged to one thus making the plan more compact.
Apart from that, you are right that the multi column transformation can lead
to further optimization opportunities. An example can be seen in query24.q.out
(Check commit
https://github.com/apache/hive/pull/1325/commits/c9f9112d0802906dce7442f3d4c01535a584af11).
There the `SharedWorkOptimizer` kicks in and merges two semijoin reducer
branches on the same scan operator.
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