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複数のテーブルからデータを取得するために複数の結合を持つクエリを作成しました。 5000以上のレコードでは非常に遅いです。私はチェックし、インデックスでは、クエリで使用される各テーブルに対して適切に設定されています。私は複数のオプションでこのクエリを最適化しようとしましたが、うまくいかず、EXPLAINまたはEXPLAIN EXTENDEDヘルプを正確に理解できません。複数の自己結合とインデックスを使って自分のMoodle mysqlクエリを高速化するには
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QUERY
EXPLAIN EXTENDED
SELECT @rownum := @rownum + 1 AS id,
u.id AS userid,
u.username AS employeeid,
u.firstname,
u.lastname,
u.email AS email,
u.city AS state,
c.fullname AS course,
c.id AS courseid,
c.fullname AS coursename,
fi2.data branchid,
fi3.data branchname,
fi6.data areaname,
fi7.data regname,
fi8.data designation,
fi9.data department,
fi10.data zone,
fi11.data branchcategory,
fi12.data branchdistrict,
fi13.data branchstate,
fi17.data gender,
fi21.data employeecategory,
fi22.data persontype,
fi23.data assignmentstatus,
fi30.data POSITION,
fi32.data dateofjoining,
fi33.data dateofbirth,
st.scoid,
st.scormid,
st.attempt,
st.value cmistarttime,
st5.value cmilessonstatus,
st5.timemodified cmitimemodified,
st3.value cmitotaltime,
st2.value cmiscore
FROM (
SELECT @rownum := 0
) r,
mdl_user u
JOIN mdl_role_assignments ra ON ra.userid = u.id
JOIN mdl_context ctx ON ctx.id = ra.contextid
JOIN mdl_course c ON c.id = ctx.instanceid
JOIN mdl_scorm s ON s.course = c.id
JOIN mdl_scorm_scoes_track st ON st.scormid = s.id AND st.userid = u.id
JOIN mdl_scorm_scoes_track AS st2 ON (u.id = st2.userid AND st2.scormid
= s.id AND st2.scoid = st.scoid AND st2.attempt = st.attempt)
JOIN mdl_scorm_scoes_track AS st3 ON (u.id = st3.userid AND st3.scormid
= s.id AND st3.scoid = st.scoid AND st3.attempt = st.attempt)
JOIN mdl_scorm_scoes_track AS st5 ON (u.id = st5.userid AND st5.scormid
= s.id AND st5.scoid = st.scoid AND st5.attempt = st.attempt)
JOIN mdl_user_info_data AS fi2 ON u.id = fi2.userid
JOIN mdl_user_info_data AS fi3 ON u.id = fi3.userid
JOIN mdl_user_info_data AS fi6 ON u.id = fi6.userid
JOIN mdl_user_info_data AS fi7 ON u.id = fi7.userid
JOIN mdl_user_info_data AS fi8 ON u.id = fi8.userid
JOIN mdl_user_info_data AS fi9 ON u.id = fi9.userid
JOIN mdl_user_info_data AS fi10 ON u.id = fi10.userid
JOIN mdl_user_info_data AS fi11 ON u.id = fi11.userid
JOIN mdl_user_info_data AS fi12 ON u.id = fi12.userid
JOIN mdl_user_info_data AS fi13 ON u.id = fi13.userid
JOIN mdl_user_info_data AS fi17 ON u.id = fi17.userid
JOIN mdl_user_info_data AS fi21 ON u.id = fi21.userid
JOIN mdl_user_info_data AS fi22 ON u.id = fi22.userid
JOIN mdl_user_info_data AS fi23 ON u.id = fi23.userid
JOIN mdl_user_info_data AS fi30 ON u.id = fi30.userid
JOIN mdl_user_info_data AS fi32 ON u.id = fi32.userid
JOIN mdl_user_info_data AS fi33 ON u.id = fi33.userid
WHERE c.id > 0 AND
u.id > 0 AND
u.deleted = 0 AND
u.suspended = 0 AND
u.confirmed = 1 AND
u.id <= 1000 AND
c.visible = 1 AND
st.element LIKE '%x.start.time%' AND
st2.element LIKE '%cmi.core.score.raw%' AND
st3.element LIKE '%cmi.core.total_time%' AND
st5.element LIKE '%cmi.core.lesson_status%' AND
fi2.fieldid = 2 AND
fi3.fieldid = 3 AND
fi6.fieldid = 6 AND
fi7.fieldid = 7 AND
fi8.fieldid = 8 AND
fi9.fieldid = 9 AND
fi10.fieldid = 10 AND
fi11.fieldid = 11 AND
fi12.fieldid = 12 AND
fi13.fieldid = 13 AND
fi17.fieldid = 17 AND
fi21.fieldid = 21 AND
fi22.fieldid = 22 AND
fi23.fieldid = 23 AND
fi30.fieldid = 30 AND
fi32.fieldid = 32 AND
fi33.fieldid = 33 AND
ra.roleid = 5 AND
ctx.contextlevel = 50
==========================
間違っている場合は私に知らせてください。 – Jon
あなたがEXPLAINを提供したことは素晴らしいことですが、基本も必要です。参照：[私は非常に単純なSQLクエリと思われるものに対してMCVEを提供するのはなぜですか？]（https://meta.stackoverflow.com/questions/333952/why-should-i-provide-an-mcve- for-what-like-to-my-to-be-a-very-simple-sql-query）を作成し、そこにテキストを書き直しましたか？それは伝えるのが難しいですが、あなたが持っているなら助けになりません。 – Strawberry
テーブルの構造やその他の詳細を表示したい場合など、他の詳細を共有したいと思います。実際には、私は以前にEXPLAINを使っておらず、正確にどこが私を指しているのか理解しようとしました。 – user2791498