mysql：一旦数据变大，查询速度就会变慢

f8rj6qna  于 2021-06-20  发布在  Mysql
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我有一个很长的查询，结果很长。可能需要15秒到20秒。在少量数据中，查询似乎还可以，我已经检查了所有索引，以及已经使用索引或where条件的所有内容。
抱歉，我没有发布实际的查询，因为它太多并且连接到其他表。
有人能帮忙吗？如果你需要进一步的信息，请告诉我。
下面是mysql的解释。

  1. 1   PRIMARY <derived2>  ALL NULL    NULL    NULL    NULL    210326  
  2. 2   DERIVED PQL ref practice_place_id,patient_id,practice_place_id_2,encounter_id,practice_place_id_3,for_comission for_comission   4   const   38950   Using where; Using index; Using temporary; Using filesort   
  3. 2   DERIVED EN  eq_ref  PRIMARY,id,practice_id,practice_id_2,practice_id_3  PRIMARY 8   PQL.encounter_id,const  1   Using index 
  4. 2   DERIVED PIH ref PRIMARY,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8    practice_id_3   12  const,EN.id 1   Using index condition; Using where  
  5. 2   DERIVED RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PQL.patient_id    1       
  6. 2   DERIVED PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   timestamp   12  PIH.timestamp,const 1   Using where 
  7. 2   DERIVED RV  eq_ref  PRIMARY PRIMARY 4   PID.item_id 1       
  8. 2   DERIVED RRV eq_ref  PRIMARY,parent_id   PRIMARY 8   PID.item_id,PID.item_sub_id 1   Using index 
  9. 2   DERIVED D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id   1   Using where 
  10. 2   DERIVED RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PIH.timestamp   1   Using where 
  11. 2   DERIVED PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  12. 2   DERIVED TL  ref reff_id reff_id 12  PIH.timestamp,const 1   Using where 
  13. 3   UNION   PQL ref practice_place_id,patient_id,practice_place_id_2,encounter_id,practice_place_id_3,for_comission for_comission   4   const   38950   Using where; Using index; Using temporary; Using filesort   
  14. 3   UNION   EN  eq_ref  PRIMARY,id,practice_id,practice_id_2,practice_id_3  PRIMARY 8   PQL.encounter_id,const  1   Using index 
  15. 3   UNION   PIH ref PRIMARY,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8    practice_id_3   12  const,EN.id 1   Using index condition; Using where  
  16. 3   UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PQL.patient_id    1       
  17. 3   UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   timestamp   12  PIH.timestamp,const 1   Using where 
  18. 3   UNION   RV  eq_ref  PRIMARY PRIMARY 4   PID.item_id 1       
  19. 3   UNION   RRV eq_ref  PRIMARY,parent_id   PRIMARY 8   PID.item_id,PID.item_sub_id 1   Using index 
  20. 3   UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id_2 1   Using where 
  21. 3   UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PIH.timestamp   1   Using where 
  22. 3   UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  23. 3   UNION   TL  ref reff_id reff_id 12  PIH.timestamp,const 1   Using where 
  24. 4   UNION   PQL ref practice_place_id,patient_id,practice_place_id_2,encounter_id,practice_place_id_3,for_comission for_comission   4   const   38950   Using where; Using index; Using temporary; Using filesort   
  25. 4   UNION   EN  eq_ref  PRIMARY,id,practice_id,practice_id_2,practice_id_3  PRIMARY 8   PQL.encounter_id,const  1   Using index 
  26. 4   UNION   PIH ref PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 practice_id_3   12  const,EN.id 1   Using index condition; Using where  
  27. 4   UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PQL.patient_id    1       
  28. 4   UNION   TL  ref reff_id reff_id 12  PIH.timestamp,const 1   Using where 
  29. 4   UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   timestamp   12  PIH.timestamp,const 1   Using where 
  30. 4   UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PIH.timestamp   1   Using where 
  31. 4   UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  32. 4   UNION   REF eq_ref  PRIMARY,practice_id,type,id,practice_id_3,id_2  PRIMARY 5   PID.item_id,PID.item_type   1   Using where 
  33. 4   UNION   DF  eq_ref  PRIMARY PRIMARY 2   REF.form    1   Using where 
  34. 4   UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id   1   Using where 
  35. 5   UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   practice_id_3   5   const,const 6533    Using index condition; Using where; Using temporary; Using filesort 
  36. 5   UNION   REF eq_ref  PRIMARY,practice_id,id,practice_id_2    PRIMARY 4   PID.item_id 1   Using where 
  37. 5   UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id   1   Using where 
  38. 5   UNION   PIH eq_ref  PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 PRIMARY 12  PID.timestamp,const 1   Using where 
  39. 5   UNION   PQL ref practice_place_id,patient_id,practice_place_id_2,encounter_id,practice_place_id_3,for_comission practice_place_id_2 9   const,PIH.reff_id   1   Using index condition; Using where  
  40. 5   UNION   EN  eq_ref  PRIMARY,id,practice_id,practice_id_2,practice_id_3  PRIMARY 8   PIH.reff_id,const   1   Using where; Using index    
  41. 5   UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PQL.patient_id    1       
  42. 5   UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PID.timestamp   1   Using where 
  43. 5   UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  44. 5   UNION   TL  ref reff_id reff_id 12  PID.timestamp,const 1   Using where 
  45. 6   UNION   PIH ref PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 practice_id_8   5   const,const 10522   Using index condition; Using temporary; Using filesort  
  46. 6   UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   timestamp   12  PIH.timestamp,const 1   Using where 
  47. 6   UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id   1   Using where 
  48. 6   UNION   REF eq_ref  PRIMARY,practice_id,type,id,practice_id_3,id_2  PRIMARY 5   PID.item_id,PID.item_type   1   Using where 
  49. 6   UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PIH.timestamp   1   Using where 
  50. 6   UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  51. 6   UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PIH.reff_id   1   Using where 
  52. 6   UNION   TL  ref reff_id reff_id 12  PIH.timestamp,const 1   Using where 
  53. 7   UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   practice_id_3   5   const,const 6533    Using index condition; Using where; Using temporary; Using filesort 
  54. 7   UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PID.timestamp   1   Using where 
  55. 7   UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  56. 7   UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id   1   Using where 
  57. 7   UNION   REF eq_ref  PRIMARY,practice_id,id,practice_id_2    PRIMARY 4   PID.item_id 1   Using where 
  58. 7   UNION   PIH eq_ref  PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 PRIMARY 12  PID.timestamp,const 1   Using where 
  59. 7   UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PIH.reff_id   1   Using where 
  60. 7   UNION   TL  ref reff_id reff_id 12  PID.timestamp,const 1   Using where 
  61. 8   UNION   PQL ref practice_place_id,patient_id,practice_place_id_2,encounter_id,practice_place_id_3,for_comission for_comission   4   const   38950   Using where; Using index; Using temporary; Using filesort   
  62. 8   UNION   EN  eq_ref  PRIMARY,id,practice_id,practice_id_2,practice_id_3  PRIMARY 8   PQL.encounter_id,const  1   Using index 
  63. 8   UNION   PIH ref PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 practice_id_3   12  const,EN.id 1   Using index condition; Using where  
  64. 8   UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PQL.patient_id    1       
  65. 8   UNION   TL  ref reff_id reff_id 12  PIH.timestamp,const 1   Using where 
  66. 8   UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   timestamp   12  PIH.timestamp,const 1   Using where 
  67. 8   UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PIH.timestamp   1   Using where 
  68. 8   UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  69. 8   UNION   REF eq_ref  PRIMARY,practice_id,type,id,practice_id_3,id_2  PRIMARY 5   PID.item_id,PID.item_type   1   Using where 
  70. 8   UNION   DF  eq_ref  PRIMARY PRIMARY 2   REF.form    1   Using where 
  71. 8   UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id_2 1   Using where 
  72. 9   UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   practice_id_3   5   const,const 6533    Using index condition; Using where; Using temporary; Using filesort 
  73. 9   UNION   REF eq_ref  PRIMARY,practice_id,id,practice_id_2    PRIMARY 4   PID.item_id 1   Using where 
  74. 9   UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id_2 1   Using where 
  75. 9   UNION   PIH eq_ref  PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 PRIMARY 12  PID.timestamp,const 1   Using where 
  76. 9   UNION   PQL ref practice_place_id,patient_id,practice_place_id_2,encounter_id,practice_place_id_3,for_comission practice_place_id_2 9   const,PIH.reff_id   1   Using index condition; Using where  
  77. 9   UNION   EN  eq_ref  PRIMARY,id,practice_id,practice_id_2,practice_id_3  PRIMARY 8   PIH.reff_id,const   1   Using where; Using index    
  78. 9   UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PQL.patient_id    1       
  79. 9   UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PID.timestamp   1   Using where 
  80. 9   UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  81. 9   UNION   TL  ref reff_id reff_id 12  PID.timestamp,const 1   Using where 
  82. 10  UNION   PIH ref PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 practice_id_8   5   const,const 10522   Using index condition; Using temporary; Using filesort  
  83. 10  UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   timestamp   12  PIH.timestamp,const 1   Using where 
  84. 10  UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id_2 1   Using where 
  85. 10  UNION   REF eq_ref  PRIMARY,practice_id,type,id,practice_id_3,id_2  PRIMARY 5   PID.item_id,PID.item_type   1   Using where 
  86. 10  UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PIH.timestamp   1   Using where 
  87. 10  UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  88. 10  UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PIH.reff_id   1   Using where 
  89. 10  UNION   TL  ref reff_id reff_id 12  PIH.timestamp,const 1   Using where 
  90. 11  UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   practice_id_3   5   const,const 6533    Using index condition; Using where; Using temporary; Using filesort 
  91. 11  UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PID.timestamp   1   Using where 
  92. 11  UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  93. 11  UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id_2 1   Using where 
  94. 11  UNION   REF eq_ref  PRIMARY,practice_id,id,practice_id_2    PRIMARY 4   PID.item_id 1   Using where 
  95. 11  UNION   PIH eq_ref  PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 PRIMARY 12  PID.timestamp,const 1   Using where 
  96. 11  UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PIH.reff_id   1   Using where 
  97. 11  UNION   TL  ref reff_id reff_id 12  PID.timestamp,const 1   Using where 
  98. 12  UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   practice_id_3   5   const,const 525 Using index condition; Using where; Using temporary; Using filesort 
  99. 12  UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id   1   Using where 
  100. 12  UNION   PIH eq_ref  PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 PRIMARY 12  PID.timestamp,const 1   Using where 
  102. 12  UNION   PQL ref practice_place_id,patient_id,practice_place_id_2,encounter_id,practice_place_id_3,for_comission practice_place_id_2 9   const,PIH.reff_id   1   Using index condition; Using where  
  103. 12  UNION   EN  eq_ref  PRIMARY,id,practice_id,practice_id_2,practice_id_3  PRIMARY 8   PIH.reff_id,const   1   Using where; Using index    
  104. 12  UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PQL.patient_id    1       
  105. 12  UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PID.timestamp   1   Using where 
  106. 12  UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  107. 12  UNION   TL  ref reff_id reff_id 12  PID.timestamp,const 1   Using where 
  108. 12  UNION   PLD ref PRIMARY,practice_id practice_id 8   const,PID.item_id   3   Using index 
  109. 12  UNION   PLI eq_ref  PRIMARY,id  PRIMARY 4   PLD.lab_item_id 1   Using index 
  110. 12  UNION   PLC eq_ref  PRIMARY PRIMARY 4   PLD.lab_cat_id  1       
  111. 13  UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   practice_id_3   5   const,const 525 Using index condition; Using where; Using temporary; Using filesort 
  112. 13  UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id   1   Using where 
  113. 13  UNION   PIH eq_ref  PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 PRIMARY 12  PID.timestamp,const 1   Using where 
  114. 13  UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PIH.reff_id   1   Using where 
  115. 13  UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PID.timestamp   1   Using where 
  116. 13  UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  117. 13  UNION   TL  ref reff_id reff_id 12  PID.timestamp,const 1   Using where 
  118. 13  UNION   PLD ref PRIMARY,practice_id PRIMARY 4   PID.item_id 4   Using where 
  119. 13  UNION   PLI eq_ref  PRIMARY,id  PRIMARY 4   PLD.lab_item_id 1   Using index 
  120. 13  UNION   PLC eq_ref  PRIMARY PRIMARY 4   PLD.lab_cat_id  1       
  121. 14  UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   practice_id_3   5   const,const 525 Using index condition; Using where; Using temporary; Using filesort 
  122. 14  UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id_2 1   Using where 
  123. 14  UNION   PIH eq_ref  PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 PRIMARY 12  PID.timestamp,const 1   Using where 
  124. 14  UNION   PQL ref practice_place_id,patient_id,practice_place_id_2,encounter_id,practice_place_id_3,for_comission practice_place_id_2 9   const,PIH.reff_id   1   Using index condition; Using where  
  125. 14  UNION   EN  eq_ref  PRIMARY,id,practice_id,practice_id_2,practice_id_3  PRIMARY 8   PIH.reff_id,const   1   Using where; Using index    
  126. 14  UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PQL.patient_id    1       
  127. 14  UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PID.timestamp   1   Using where 
  128. 14  UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  129. 14  UNION   TL  ref reff_id reff_id 12  PID.timestamp,const 1   Using where 
  130. 14  UNION   PLD ref PRIMARY,practice_id practice_id 8   const,PID.item_id   3   Using index 
  131. 14  UNION   PLI eq_ref  PRIMARY,id  PRIMARY 4   PLD.lab_item_id 1   Using index 
  132. 14  UNION   PLC eq_ref  PRIMARY PRIMARY 4   PLD.lab_cat_id  1       
  133. 15  UNION   PID ref item_type,timestamp,practice_id,item_id_2,timestamp_2,practice_id_2,practice_id_3   practice_id_3   5   const,const 525 Using index condition; Using where; Using temporary; Using filesort 
  134. 15  UNION   D   ref doc_id,pp_id,id_2,pp_doc    doc_id  4   PID.doctor_id_2 1   Using where 
  135. 15  UNION   PIH eq_ref  PRIMARY,source,reff_id,practice_id,timestamp,is_active,practice_id_3,cal_id,practice_id_5,practice_id_6,practice_id_2,practice_id_4,practice_id_7,practice_id_8 PRIMARY 12  PID.timestamp,const 1   Using where 
  136. 15  UNION   RPP eq_ref  PRIMARY,patient_id,practice_id,practice_id_2    PRIMARY 8   const,PIH.reff_id   1   Using where 
  137. 15  UNION   RPIP    ref timestamp,practice_id,timestamp_2,refunded  timestamp   8   PID.timestamp   1   Using where 
  138. 15  UNION   PIC ref practice_id,prc_invoice_detail_id,claim_status,practice_id_2,practice_id_3,practice_id_4,practice_id_5  practice_id 4   const   1   Using where 
  139. 15  UNION   TL  ref reff_id reff_id 12  PID.timestamp,const 1   Using where 
  140. 15  UNION   PLD ref PRIMARY,practice_id PRIMARY 4   PID.item_id 4   Using where 
  141. 15  UNION   PLI eq_ref  PRIMARY,id  PRIMARY 4   PLD.lab_item_id 1   Using index 
  142. 15  UNION   PLC eq_ref  PRIMARY PRIMARY 4   PLD.lab_cat_id  1
mysqlindexingexplain

1条答案

按热度按时间
tpxzln5u

tpxzln5u1#

“我已经检查了所有索引，以及已经使用索引或where条件的所有内容。”—不够好。 Using index condition 可能意味着“综合”指数会有所帮助。让我们看看 SHOW CREATE TABLEs .
让我们看一张8桌 UNIONs .
你用的是什么版本？旧版本在处理多个“派生”表时做得很糟糕——因为没有索引。
结果集真的有210k行吗？或者是有一个 LIMIT 我们看不见的？

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