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  1. Hive
  2. HIVE-7292 Hive on Spark
  3. HIVE-8054

Disable hive.optimize.union.remove when hive.execution.engine=spark [Spark Branch]

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    Description

      Option hive.optimize.union.remove introduced in HIVE-3276 removes union operators from the operator graph in certain cases as an optimization reduce the number of MR jobs. While making sense in MR, this optimization is actually harmful to an execution engine such as Spark, which natives supports union without requiring additional jobs. This is because removing union operator creates disjointed operator graphs, each graph generating a job, and thus this optimization requires more jobs to run the query. Not to mention the additional complexity handling linked FS descriptors.

      I propose that we disable such optimization when the execution engine is Spark.

      Attachments

        1. HIVE-8054-spark.patch
          136 kB
          Na Yang
        2. HIVE-8054.2-spark.patch
          141 kB
          Na Yang
        3. HIVE-8054.3-spark.patch
          145 kB
          Na Yang

        Issue Links

          is part of

          Improvement - An improvement or enhancement to an existing feature or task. HIVE-7292 Hive on Spark

          • Major - Major loss of function.
          • Resolved
          is related to

          Task - A task that needs to be done. HIVE-8073 Go thru all operator plan optimizations and disable those that are not suitable for Spark [Spark Branch]

          • Major - Major loss of function.
          • Closed
          relates to

          Sub-task - The sub-task of the issue HIVE-8055 Code cleanup after HIVE-8054 [Spark Branch]

          • Major - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. HIVE-3276 optimize union sub-queries

          • Major - Major loss of function.
          • Closed

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              nyang Na Yang
              xuefuz Xuefu Zhang
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                Updated:
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