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  1. MariaDB Server
  2. MDEV-25845

Remove one SELECT_DESCRIBE check in JOIN::optimize_inner()

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    Details

    • Type: Task
    • Status: Open (View Workflow)
    • Priority: Major
    • Resolution: Unresolved
    • Fix Version/s: 10.7
    • Component/s: Optimizer
    • Labels:
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      Description

      This is a followup to MDEV-25576, this part:

      https://jira.mariadb.org/browse/MDEV-25576?focusedCommentId=190651&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-190651

      JOIN::optimize_inner has this code

        if (const_table_map != found_const_table_map &&
            !(select_options & SELECT_DESCRIBE))
        {
          // There is at least one empty const table
          zero_result_cause= "no matching row in const table";
          ...
          goto setup_subq_exit;
      

      The !(select_options & SELECT_DESCRIBE)) part is bad practice.

      Removing it causes a lot of changes in EXPLAIN output.

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              Assignee:
              psergei Sergei Petrunia
              Reporter:
              psergei Sergei Petrunia
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                Updated:

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