Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-25846

Remove one SELECT_DESCRIBE check in JOIN::optimize_inner()

    XMLWordPrintable

Details

    • Task
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Duplicate
    • N/A
    • Optimizer
    • None

    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.

      Attachments

        Issue Links

          Activity

            People

              psergei Sergei Petrunia
              psergei Sergei Petrunia
              Votes:
              0 Vote for this issue
              Watchers:
              1 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved:

                Git Integration

                  Error rendering 'com.xiplink.jira.git.jira_git_plugin:git-issue-webpanel'. Please contact your Jira administrators.