UNION或UNION ALL MYSQL OPTIMIZATION

我一直在试图优化下面的MySQL查询无济于事。目前，它最多需要3秒，执行：UNION或UNION ALL MYSQL OPTIMIZATION

select count(DISTINCT v.id) from 
( 
    select sub_jobs.id from sub_jobs, main_jobs where sub_jobs.title LIKE '%abc%' and main_jobs.id=sub_jobs.parent_id 

    UNION ALL 

    select sub_jobs.id from sub_jobs, main_jobs where job_title LIKE '%abc%' and main_jobs.id=sub_jobs.parent_id 

    UNION ALL 

    select sub_jobs.id from sub_jobs, main_jobs, companies where companies.company_name LIKE '%abc%' and main_jobs.company_id=companies.id and main_jobs.id=sub_jobs.parent_id 
) 
as v

怎么做我想做的事：

搜索三列3代表的关键字，并返回重复计数

基本表结构：

个1. sub_jobs

ID
标题[I要搜索该列]
PARENT_ID

2. main_jobs

ID
JOB_TITLE [我想要t Ø搜索此列]
COMPANY_ID [某些行不具备此列中的条目]

3.公司

ID
COMPANY_NAME [我要搜索此列]

EXPLAIN

------column titles------ 

id 
select_type: 
table 
type 
possible_keys 
key 
key_len 
ref 
rows 
Extra 

--- row 1 ---- 

id: 1 
select_type: PRIMARY 
table: <derived2> 
ALL 
NULL 
NULL 
NULL 
NULL 
102642 
NULL 


---- row 2 ---- 

id: 2 
select_type: DERIVED 
table: main_jobs 
index 
PRIMARY,id_index,id_industry_featured_index 
id_index 
4 
NULL 
34214 
Using index 


---- row 3 ---- 

id: 2 
select_type: DERIVED 
table: sub_jobs 
ref 
parent_id,parent_id_category_index 
parent_id 
4 
myjobmag_myjobdb.main_jobs.id 
1 
Using where 


---- row 4 ---- 

id: 3 
select_type: UNION 
table: main_jobs 
ALL 
PRIMARY,id_index,id_industry_featured_index 
NULL 
NULL 
NULL 
34214 
Using where 

---- row 5 ---- 

id: 3 
select_type: UNION 
table: sub_jobs 
ref 
parent_id,parent_id_category_index 
parent_id 
4 
main_jobs.id 
1 
Using index 

---- row 6 ---- 


id: 4 
select_type: UNION 
table: main_jobs 
ALL 
PRIMARY,id_index,id_industry_featured_index 
NULL 
NULL 
NULL 
34214 
NULL 

---- row 7 ---- 

id: 4 
select_type: UNION 
table: companies 
eq_ref 
PRIMARY 
PRIMARY 
4 
main_jobs.company_id 
1 
Using where 


---- row 8 ---- 

id: 4 
select_type: UNION 
table: sub_jobs 
ref 
parent_id,parent_id_category_index 
parent_id 
4 
main_jobs.id 
1 
Using index 


---- row 9 ---- 

id: NULL 
select_type: UNION RESULT 
table: <union2,3,4> 
ALL 
NULL 
NULL 
NULL 
NULL 
NULL 
Using temporary

我试过使用没有DISTINCT的UNION没有显着的收益。

如何减少此查询的运行时间。

来源

2017-07-11 Ogugua Belonwu

试图减少一个条件。请尝试，让我知道

select count(DISTINCT v.id) from 
( 
    select sub_jobs.id 
    from sub_jobs inner join main_jobs 
    on main_jobs.id=sub_jobs.parent_id 
    where (sub_jobs.title LIKE '%abc%' OR job_title LIKE '%abc%') 

    UNION ALL 

    select sub_jobs.id 
    from sub_jobs, main_jobs, companies 
    where companies.company_name LIKE '%abc%' and 
      main_jobs.company_id=companies.id and 
      main_jobs.id=sub_jobs.parent_id 
) 
as v

编辑问题，更新后

是可能的2个查询组合是这样的：

select count(DISTINCT v.id) from 
( 
    select sub_jobs.id 
    from sub_jobs 
     inner join main_jobs 
      on main_jobs.id=sub_jobs.parent_id 
     inner join companies 
      on main_jobs.company_id=companies.id 
    where companies.company_name LIKE '%abc%' 
      OR 
      sub_jobs.title LIKE '%abc%' 
      OR 
      job_title LIKE '%abc%'  
) 
as v

让我知道，如果是工作或抛出错误

来源

2017-07-11 18:33:20

谢谢您的帮助。没有明显的变化。 –

你可以尝试使用一个单一的队列，或代替3个查询与联盟

，但你应该看看说明计划

select count(dictinnct sub_jobs.id) 
    from sub_jobs 
    INNER JOIN main_jobs on main_jobs.id=sub_jobs.parent_id 
    INNER JOIN companies on main_jobs.company_id=companies.id 
    where companies.company_name LIKE '%abc%' 
    OR main_jobs.job_title LIKE '%abc%' 
    OR sub_jobs.title LIKE '%abc%'

来源

2017-07-11 18:37:38 scaisEdge

UNION或UNION ALL MYSQL OPTIMIZATION

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