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  1. Hive
  2. HIVE-11617 Explain plan for multiple lateral views is very slow
  3. HIVE-11799

The output of explain query for multiple lateral views is huge

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Details

    • Sub-task
    • Status: Patch Available
    • Major
    • Resolution: Unresolved
    • 2.0.0
    • None
    • Hive
    • None

    Description

      Execute the following query

      CREATE TABLE `t1`(`pattern` array<int>);
        
      explain select * from t1 
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1
      lateral view explode(pattern) tbl1 as col1;
      

      After HIVE-11617 gets fixed, the explain output still takes forever since we are recursively printing operator info which could be an issue if the ops could have multiple children and parents, like lateral view case. Right now, if a node has multiple parents, then it including its descendants will be printed multiple times. We should print once and probably print just a reference later on.

      Attachments

        1. HIVE-11799.patch
          0.6 kB
          Aihua Xu

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            aihuaxu Aihua Xu
            aihuaxu Aihua Xu
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            Dates

              Created:
              Updated: