UNION或UNION ALL MYSQL OPTIMIZATION

我一直在試圖優化下面的MySQL查詢無濟於事。目前，它最多需要3秒，執行：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

怎麼做我想做的事：

搜索三列3代表的關鍵字，並返回重複計數

基本表結構：

個1. sub_jobs

ID
標題[I要搜索該列]
PARENT_ID

2. main_jobs

ID
JOB_TITLE [我想要t Ø搜索此列]
COMPANY_ID [某些行不具備此列中的條目]

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

我試過使用沒有DISTINCT的UNION沒有顯着的收益。

如何減少此查詢的運行時間。

來源

2017-07-11 Ogugua Belonwu

試圖減少一個條件。請嘗試，讓我知道

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

編輯問題，更新後

是可能的2個查詢組合是這樣的：

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

讓我知道，如果是工作或拋出錯誤

來源

2017-07-11 18:33:20

謝謝您的幫助。沒有明顯的變化。 –

你可以嘗試使用一個單一的隊列，或代替3個查詢與聯盟

，但你應該看看說明計劃

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%'

來源

2017-07-11 18:37:38 scaisEdge

UNION或UNION ALL MYSQL OPTIMIZATION

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