Moodle加入查询速度慢

Question

我已经在这件事上好几个小时了。有没有人对如何加快查询速度有任何想法？

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中有超过100,000行，并且正在减慢所有内容。