mysql - この MySQL クエリを最適化してより高速に実行する方法に関する提案

Question

SELECT * 
FROM   members 
WHERE  memberid IN (SELECT follows.followingid 
                    FROM   follows 
                    WHERE  follows.memberid = '$memberid' 
                           AND follows.followingid NOT IN (SELECT memberid 
                                                           FROM   userblock)) 
       AND memberid NOT IN (SELECT blockmemberid 
                            FROM   userblock 
                            WHERE  memberid = '$memberid')

上記のクエリは、MySQL での実行に 4 秒近くかかっています。実行時間を短縮するためにクエリを改善/最適化する方法について誰か提案があるかどうか知りたいですか?

Answer 1

SELECT m.* 
FROM   members m
INNER JOIN follows f ON f.followingid = m.memberid AND
                        f.memberid = '$memberid'
LEFT OUTER JOIN userblock ub1 ON f.followingid = ub1.memberid 
LEFT OUTER JOIN userblock ub2 ON m.memberid = ub2.blockmemberid AND
                            ub2.memberid = '$memberid'
WHERE ub1.memberid IS NULL AND ub2.blockmemberid IS NULL