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  1. Hadoop Common
  2. HADOOP-4084

Add explain plan capabilities to Hive QL

    Details

    • Type: New Feature
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 0.19.0
    • Component/s: None
    • Labels:
      None
    • Hadoop Flags:
      Reviewed
    • Release Note:
      Introduced "EXPLAIN" plan for Hive.

      Description

      Adding explain plan for queries in hive.

      The current proposal is to support something like:

      EXPLAIN [EXTENDED]
      SELECT ....

      This will output the following:

      Abstract Syntax Tree:

      Number of Stages:

      Dependencies between Stages:

      Plan for each stage:

      If EXTENDED keyword is used then much more information will be emitted where as without that keyword only logical information will be emitted.

      e.g. In case of a group by query

      EXPLAIN
      SELECT T.c1, count(1) FROM T GROUP BY T.c1;

      The explain plan itself has two stages

      Stage1 and Stage2

      Stage1 will have the plan for generating the partial aggregates
      and Stage2 will have the plan for generating the complete aggregates.

      I also plan to convert the parse and semantic analysis tests so that they use this for finding differences in the plan instead of the programmatic plan dumps that we are using today (tests/queries/positive).

        Attachments

        1. patch-4084
          464 kB
          Ashish Thusoo
        2. patch-4084
          464 kB
          Ashish Thusoo
        3. patch-4084_v3
          544 kB
          Ashish Thusoo

          Activity

            People

            • Assignee:
              athusoo Ashish Thusoo
              Reporter:
              athusoo Ashish Thusoo
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              Dates

              • Created:
                Updated:
                Resolved: