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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

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              Unassigned Unassigned
              baleevskii Grigory Baleevskiy
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              Dates

                Created:
                Updated:
                Resolved:

                Clockify

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