MySQL查詢不使用索引i想

我有以下查詢左接合2個表：在該表NPI哪些索引MySQL查詢不使用索引i想

npi_fname_lname_state_city_zip_entity：

explain 

    select 
     n.* from npi n left join npi_taxonomy nt on n.NPI=nt.NPI_CODE 

    where 
     n.Provider_First_Name like '%s%' and 
     n.Provider_Last_Name like '%b%' and 
     n.Provider_Business_Practice_Location_Address_State_Name = 'SC' and 
     n.Provider_Business_Practice_Location_Address_City_Name = 'charleston' and 
     n.Provider_Business_Practice_Location_Address_Postal_Code in (29001,29003,29010,29016,29018,29020,29030,29032,29033,29038,29039,29040,29041,29042,29044,29045,29046,29047,29048,29051,29052,29053,29056,29059,29061,29062,29069,29071,29072,29073,29078,29079,29080,29081,29082,29102,29104,29107,29111,29112,29113,29114,29115,29116,29117,29118,29123,29125,29128,29133,29135,29137,29142,29143,29146,29147,29148,29150,29151,29152,29153,29154,29160,29161,29162,29163,29164,29168,29169,29170,29171,29172,29201,29202,29203,29204,29205,29206,29207,29208,29209,29210,29212,29214,29215,29216,29217,29218,29219,29220,29221,29222,29223,29224,29225,29226,29227,29228,29229,29230,29240,29250,29260,29290,29292,29401,29402,29403,29404,29405,29406,29407,29409) and 
     n.Entity_Type_Code = 1 and 
     nt.Healthcare_Provider_Taxonomy_Code in ('101Y00000X') 

    limit 0,10;

我添加了一個多列索引列按以下順序：

NPI, 
Provider_First_Name, 
Provider_First_Name, 
Provider_Business_Practice_Location_Address_State_Name, Provider_Business_Practice_Location_Address_City_Name, Provider_Business_Practice_Location_Address_Postal_Code, 
Entity_Type_Code

但是，當我做了一個關於查詢的解釋，它表明它使用t他主要指標（NPI）。此外，它說行檢查= 1

更糟糕的是：查詢大致需要秒執行。我如何優化這個？

我真的很感謝這方面的幫助。

來源

2011-03-07 Yash Desai

有關[_constructing indexes_]（http://mysql.rjweb.org/doc.php/index_cookbook_mysql）和[_pagination_]（http://mysql.rjweb.org/doc.php/pagination）的更多信息。 – 2017-01-11 19:41:26

多列索引無法解決的原因是因爲您正在使用通配符like '%s%'進行篩選。過濾使用離開指數，這意味着1）cannot do a contains search的最前綴時，和

索引只能用2）如果無法使用多列索引的最左列，其他列中索引cannot be used aswell。

你應該在索引中的列的順序切換到

Provider_Business_Practice_Location_Address_State_Name, 
Provider_Business_Practice_Location_Address_City_Name, 
Provider_Business_Practice_Location_Address_Postal_Code, 
Entity_Type_Code

這樣，MySQL將只掃描匹配的標準，這些列（SC，查爾斯頓等）的行。

或者，查看full text indexes。

來源

2011-03-08 00:59:26

MySQL查詢不使用索引i想

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