mysql - Moodle結合クエリが遅い

Question

私は何時間もこのことに取り組んできました。このクエリを高速化する方法について誰かがアイデアを持っていますか？

SELECT SQL_CALC_FOUND_ROWS
mdl_course.fullname as course_name,
mdl_course.idnumber as course_length,
mdl_user.firstname as firstname,
mdl_user.lastname as lastname,

case when mdl_course_completions.timecompleted IS NOT NULL
then FROM_UNIXTIME(mdl_course_completions.timecompleted,'%m/%d/%Y') else 'N/A' end AS date_completed,

mdl_cohort.name AS group_name,
mdl_course_categories.name as category_name,

case when mdl_course_completions.timecompleted IS NOT NULL then 'Completed' else
'Incomplete' end AS completion_status
FROM mdl_enrol
JOIN mdl_user_enrolments    ON mdl_user_enrolments.enrolid  = mdl_enrol.id
JOIN mdl_course             ON mdl_course.id                = mdl_enrol.courseid        
JOIN mdl_user               ON mdl_user.id                  = mdl_user_enrolments.userid AND mdl_user.deleted = 0
JOIN mdl_cohort_members     ON mdl_cohort_members.userid    = mdl_user.id
JOIN mdl_cohort             ON mdl_cohort.id                = mdl_cohort_members.cohortid
JOIN mdl_course_categories  ON mdl_course_categories.id     = mdl_course.category

JOIN mdl_course_completions ON mdl_course_completions.course = mdl_course.id
AND mdl_course_completions.userid = mdl_user.id
AND mdl_course_completions.deleted IS NULL


GROUP BY mdl_course_completions.id
ORDER BY mdl_course.fullname ASC

mdl_course_completionsには100,000を超える行があり、すべての速度が低下しています。