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Posted to issues@spark.apache.org by "Reynold Xin (JIRA)" <ji...@apache.org> on 2015/07/22 20:55:04 UTC

[jira] [Created] (SPARK-9258) Remove BroadcastLeftSemiJoinHash

Reynold Xin created SPARK-9258:
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             Summary: Remove BroadcastLeftSemiJoinHash
                 Key: SPARK-9258
                 URL: https://issues.apache.org/jira/browse/SPARK-9258
             Project: Spark
          Issue Type: Improvement
          Components: SQL
            Reporter: Reynold Xin


We have too many join operators than our resources to optimize them. In this case, BroadcastLeftSemiJoinHash isn't very necessary. We can still use an equi-join operator to do the join, and just not include any values from the other join.

We waste a little bit space due to building a hash map rather than a hash set, but at the end of the day unless we are going to spend a lot of time optimizing hash set, our Tungsten hash map will be a lot more efficient than the hash set anyway ...





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