Uploaded image for project: 'Moodle'
  1. Moodle
  2. MDL-52801

healthcheck hangs up on a certain set of data: introduce new DML aggregation method for concatenation

    XMLWordPrintable

Details

    Description

      problem_000013 class from admin/tool/health/index.php sends an unoptimal database query which makes N*M scans in the database (N,M - number of rows in

      {question}

      ,

      {question_multianswer}

      accordingly) which is very time-consuming process.

      TO REPRODUCE:
      create 500k records in both tables and try to run
      /admin/tool/health/index.php script

      WHAT EXPECTED:
      linear complexity at least. Execution time < 30 seconds

      WHAT HAPPENED:
      N^2 complexity. Execution time > 900 seconds

      Attachments

        Issue Links

          Activity

            People

              Unassigned Unassigned
              baleevskii Grigory Baleevskiy
              David Woloszyn, Huong Nguyen, Jake Dallimore, Meirza, Michael Hawkins, Raquel Ortega, Safat Shahin, Stevani Andolo, David Woloszyn, Huong Nguyen, Jake Dallimore, Meirza, Michael Hawkins, Raquel Ortega, Safat Shahin, Stevani Andolo, Safat Shahin, Tim Hunt, Ilya Tregubov, Kevin Percy, Mathew May, Mihail Geshoski, Shamim Rezaie
              Votes:
              1 Vote for this issue
              Watchers:
              7 Start watching this issue

              Dates

                Created:
                Updated: