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  1. Moodle
  2. MDL-73727

Improve get_conversions_for_file query performance on large sites

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      There's a seq scan that's occurring in the query produced by `get_conversions_for_file` (files/classes/conversion.php)

      For some reason, Postgres is choosing to do that rather than use one of the indexes. This query is regularly sitting in the top 4 for CPU on both the various reader and writer instances we're using.

      Also I've tested this on a smaller site and the issue wasn't apparent. I've only observed this on larger sites.

        1. explain-diff.png
          explain-diff.png
          102 kB
        2. FileConversion Tests (after).txt
          2 kB
        3. FileConversion Tests (before).txt
          2 kB

            kevinpham Kevin Pham
            kevinpham Kevin Pham
            Brendan Heywood Brendan Heywood
            Sara Arjona (@sarjona) Sara Arjona (@sarjona)
            CiBoT CiBoT
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