我正在尝试运行一个查询，该查询需要5秒才能执行100000行。查询如下。我已经尝试了所有可能的索引。请告诉我我错过了什么。
select distinct db_books.bookid as id
, request_type.name as book_type
, request_type.id as book_type_id
, db_books.subject as subject
, sender_user.uid as sender_user_id
, sender_user.username as sender_user
, sender_company.companyid as sender_company_id
, sender_company.companyname as sender_company
, sender_team_id.teamid as sender_team_id
, sender_team_id.name as sender_team
, GROUP_CONCAT(distinct receiver_user_details.uid separator '|') as receiver_user_id
, GROUP_CONCAT(distinct receiver_user_details.username separator '|') as receiver_user
, GROUP_CONCAT(distinct receiver_company.companyid separator '|') as receiver_company_id
, GROUP_CONCAT(distinct receiver_company.companyname separator '|') as receiver_company
, GROUP_CONCAT(distinct receiver_team_details.teamid separator '|') as receiver_team_id
, GROUP_CONCAT(distinct receiver_team_details.name separator '|') as receiver_team
, status.id as statusid
, status.name as status
, db_books.modifydate as modified_date
, db_books.createddate as creation_date
, state.id as stateid
, state.name as state
, assignee.uid as assignee_user_id
, assignee.username as assignee_user
, purpose.name as purpose
, purpose.id as purposeid
, g.name as entityname
, g.entityid as entityid
from db_books db_books
inner join db_users sender_user on (sender_user.deleted=0 and sender_user.uid=db_books.sndrUserid)
inner join db_companies sender_company on (sender_company.deleted=0 and sender_company.companyid=db_books.sndrCompanyid)
inner join db_companies receiver_company on (receiver_company.deleted=0 and receiver_company.companyid=db_books.target_company_id)
inner join db_request_types request_type on (request_type.id=db_books.book_type_id)
left outer join db_teams sender_team_id on (sender_team_id.deleted=0 and sender_team_id.teamid=db_books.sender_team_id)
left outer join db_books_to_users receiver_user on (receiver_user.bookid=db_books.bookid)
left outer join db_users receiver_user_details on (receiver_user_details.uid=receiver_user.userid)
left outer join db_books_to_teams receiver_teams on (receiver_teams.bookid=db_books.bookid)
left outer join db_teams receiver_team_details on (receiver_team_details.teamid=receiver_teams.teamid)
left outer join db_request_status status on (status.id=db_books.statusid)
left outer join db_request_state_types state on (state.id=db_books.request_state_id)
left outer join db_request_purpose purpose on (purpose.id=db_books.request_purpose_id)
left outer join db_users assignee on (assignee.uid=db_books.assignee)
left outer join db_books_details mdtl on (mdtl.deleted=0 and mdtl.bookid=db_books.bookid)
left outer join db_entities g on (g.deleted=0 and g.entityid=mdtl.entityid)
where 1=1
and
(db_books.sndrUserid=25000000003265
or db_books.sender_team_id in (
select a.teamid from db_team_users a
inner join db_teams b on (b.teamid=a.teamid and b.deleted=0)
where a.userid=25000000003265
)
or db_books.bookid in (
select distinct bookid from db_books_to_users where userid=25000000003265
union
select distinct bookid from db_books_to_teams where teamid in
(
select a.teamid from db_team_users a
inner join db_teams b on (b.teamid=a.teamid and b.deleted=0)
where a.deleted=0 AND a.userid=25000000003265
)
)
)
group by db_books.bookid
limit 20
解释计划如下：
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY sender_user ALL PRIMARY,u2 14573 Using where; Using temporary; Using filesort
1 PRIMARY db_books ref i_db_books_target_company_id,i_db_books_sndrUserid,i_db_books_sndrCompanyid,i_sndrUserid_sender_team_idbookid i_db_books_sndrUserid 7 mde_staging.sender_user.uid 41 Using where
1 PRIMARY sender_company eq_ref PRIMARY,db_companies_icd PRIMARY 7 mde_staging.db_books.sndrCompanyid 1 Using where
1 PRIMARY receiver_company eq_ref PRIMARY,db_companies_icd PRIMARY 7 mde_staging.db_books.target_company_id 1 Using where
1 PRIMARY sender_team_id eq_ref PRIMARY,db_teams_i PRIMARY 7 mde_staging.db_books.sender_team_id 1
1 PRIMARY receiver_user ref i_db_books_to_users_bookid i_db_books_to_users_bookid 7 mde_staging.db_books.bookid 1
1 PRIMARY receiver_user_details eq_ref PRIMARY,u2 PRIMARY 7 mde_staging.receiver_user.userid 1
1 PRIMARY receiver_teams ref i_db_books_to_teams_bookid i_db_books_to_teams_bookid 7 mde_staging.db_books.bookid 1
1 PRIMARY receiver_team_details eq_ref PRIMARY,db_teams_i PRIMARY 7 mde_staging.receiver_teams.teamid 1
1 PRIMARY status eq_ref PRIMARY PRIMARY 4 mde_staging.db_books.statusid 1
1 PRIMARY state eq_ref PRIMARY PRIMARY 4 mde_staging.db_books.request_state_id 1
1 PRIMARY purpose eq_ref PRIMARY PRIMARY 4 mde_staging.db_books.request_purpose_id 1
1 PRIMARY assignee eq_ref PRIMARY,u2 PRIMARY 7 mde_staging.db_books.assignee 1
1 PRIMARY mdtl ref db_books_details_bookid db_books_details_bookid 7 mde_staging.db_books.bookid 1
1 PRIMARY request_type ALL PRIMARY 4 Using where; Using join buffer
1 PRIMARY g eq_ref PRIMARY,db_entities7 PRIMARY 7 mde_staging.mdtl.entityid 1
3 DEPENDENT SUBQUERY db_books_to_users ref i_db_books_to_users_bookid i_db_books_to_users_bookid 7 func 1 Using where; Using temporary
4 DEPENDENT UNION db_books_to_teams ref i_db_books_to_teams_bookid i_db_books_to_teams_bookid 7 func 1 Using where; Using temporary
5 DEPENDENT SUBQUERY b eq_ref PRIMARY,db_teams_i PRIMARY 7 func 1 Using where
5 DEPENDENT SUBQUERY a ref db_team_users_i db_team_users_i 11 func,const 1 Using where
UNION RESULT <union3,4> ALL
2 DEPENDENT SUBQUERY b eq_ref PRIMARY,db_teams_i PRIMARY 7 func 1 Using where
2 DEPENDENT SUBQUERY a ref db_team_users_i db_team_users_i 7 func 1 Using where
如果你看到解释计划的第一行，它没有使用可能的索引，然后使用文件排序等。不确定这是否是问题。请建议我如何修复这个或我使用什么索引??
答案 0 :(得分：0)
我看到的最大问题是子查询限定符。每行测试一次。然后我会将WHERE子句部分更改为仅作为第一个表的预查询，并获得那些结果书并加入书籍，其余应该没问题。此外，“STRAIGHT_JOIN”子句告诉引擎按照你说的顺序进行查询。有时候，它会超前于你，并尝试根据其中一个“查找”参考表进行优化，然后回填其余部分。所有这一切，
将顶部的SELECT更改为
select STRAIGHT_JOIN distinct
然后你的from子句来自
from
db_books db_books
到
from
( SELECT distinct db.bookid
from
db_books db
left join db_team_users TeamA
ON db.sndrUserID = TeamA.userID
AND db.Sender_Team_ID = TeamA.TeamID
LEFT JOIN db_teams TeamB
ON TeamA.TeamID = TeamB.TeamID
AND TeamB.Deleted = 0
left join db_books_to_users ToUser
ON db.BookID = ToUser.BookID
AND db.sndrUserID = ToUser.userID
left join db_books_to_teams ToTeamA
ON db.TeamID = ToTeamA.TeamID
AND db.sndrUserID = ToTeamA.UserID
AND a.Deleted = 0
left join db_teams ToTeamsB
ON ToTeamA.TeamID = ToTeamB.TeamID
AND b.Deleted = 0
where
db.sndrUserID = 25000000003265
OR NOT TeamB.TeamID IS NULL
OR NOT ToUser.BookID IS NULL
OR NOT ToTeamB.TeamID IS NULL
limit
20 ) PreQualBooks
JOIN db_books
ON PreQualBooks.BookID = db_Books.BookID
您可以删除Final WHERE子句，因为此预先查询将在前面完成，以根据用户或团队与JOIN的关系对每个可能的书籍ID进行预先鉴定。通过允许LEFT JOIN，books表通过ONCE，具有与团队/用户状态的所有相应关系，并且将仅基于发送用户或相应LEFT JOIN的最低级别（TeamB，ToUser和ToTeamB）返回那些记录。此预先查询还将限制应用于20本书，因此不需要查询结尾处的LIMIT子句，因为只有20本书可能是可能的。
由于你的group_concat而离开你的外部GROUP BY。