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  1. Moodle
  2. MDL-52801

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

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    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

          has a non-specific relationship to

          Improvement - An enhancement to an existing Moodle feature. MDL-52817 New sql_group_concat db method

          • Minor - Minor loss of function where workaround is possible
          • Closed
          has been marked as being related by

          Improvement - An enhancement to an existing Moodle feature. MDL-67818 Create a Check API

          • Minor - Minor loss of function where workaround is possible
          • Closed
          will be (partly) resolved by

          Improvement - An enhancement to an existing Moodle feature. MDL-67228 Set tool_replace maturity

          • Minor - Minor loss of function where workaround is possible
          • Closed

          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
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              Dates

                Created:
                Updated: