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  1. MariaDB Server
  2. MDEV-6498

SHOW EXPLAIN and PERFORMANCE_SCHEMA integration

    Details

    • Type: Task
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Fix Version/s: 10.2
    • Component/s: None
    • Labels:
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      Description

      (Ideas based on initial discussion with Stephane VAROQUI in Budapest.

      SHOW EXPLAIN feature should be integrated with PERFORMANCE_SCHEMA.

      PERFORMANCE_SCHEMA has tables that describe statements together with information about their execution:

      1. events_statements_current
      2. events_statements_history
      3. events_statements_history_long
      4. events_statements_summary_by_digest

      #1-#3 have info about individual statements, #4 describes a group of statements with the same digest.

      As for #1-#3:
      The straightforward decision is to add a column with EXPLAIN info. On the other hand, it will add extra mem/cpu overhead for those who don't need it. Maybe, it is better to keep EXPLAINs in a separate table.

      As for #4, there is a question which query plans should be there. Maybe, we should provide query plans from the best and the worst execution? The idea about putting EXPLAINs in a separate table applies here, too.

      In case we store EXPLAINs in a separate table(s), we could use P_S.setup_consumers to control whether EXPLAINs would be saved.

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              • Assignee:
                psergey Sergei Petrunia
                Reporter:
                psergey Sergei Petrunia
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                • Created:
                  Updated: