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  1. Moodle
  2. MDL-65429

Include unsubscribes in the forum subscription cache to improve performance

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      When looking to some DB performance problems @ MDL-65069, it was detected that this query:

      SELECT id, discussion, preference FROM mdl_forum_discussion_subs WHERE userid = $1 AND forum = $2 array (
        0 => '2',
        1 => 107,
      )
      

      Is executed 65 times in a forum/view page plenty of discussions.

      Tracing down the problem... it seems that mod_foum\subscriptions::fill_discussion_subscription_cache() does not cache query misses... and that causes the same query to be executed as many times as discussions are in a page.

      This should be fixed in all supported branches because they are lots of queries for nothing.

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              peterdias Peter Dias
              stronk7 Eloy Lafuente (stronk7)
              Neill Magill Neill Magill
              Andrew Lyons Andrew Lyons
              CiBoT CiBoT
              Andrew Lyons, Huong Nguyen, Jun Pataleta, Michael Hawkins, Shamim Rezaie, Simey Lameze, Andrew Lyons, Huong Nguyen, Jun Pataleta, Michael Hawkins, Shamim Rezaie, Simey Lameze, Matteo Scaramuccia, Andrew Lyons, Huong Nguyen, Jun Pataleta, Michael Hawkins, Shamim Rezaie, Simey Lameze
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              Dates

                Created:
                Updated:
                Resolved:
                11/Nov/19

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