实践社区首页的'最热'tab的性能优化

app/controllers/subjects_controller.rb

@@ -22,17 +22,17 @@ class SubjectsController < ApplicationController
     # 最热排序
     if reorder == "myshixun_count"
       if select
-        @subjects = Subject.find_by_sql("SELECT subjects.id, subjects.name, subjects.stages_count, subjects.repertoire_id, subjects.status,
-                            subjects.shixuns_count, COUNT(myshixuns.id) AS myshixun_member_count FROM myshixuns, stage_shixuns, subjects
-                            WHERE myshixuns.shixun_id = stage_shixuns.shixun_id AND stage_shixuns.subject_id = subjects.id
-                            AND `subjects`.`hidden` = 0 AND `subjects`.`status` = 2 AND `subjects`.`name` like '%#{search}%'
-                            AND `subjects`.`repertoire_id` = #{select} GROUP BY subjects.id ORDER BY myshixun_member_count DESC")
+        @subjects = Subject.find_by_sql("SELECT subjects.id, subjects.user_id, subjects.name, subjects.stages_count, subjects.repertoire_id, subjects.status,
+                      subjects.shixuns_count, sum(shixuns.myshixuns_count) AS myshixun_member_count FROM subjects join stage_shixuns
+                      on stage_shixuns.subject_id = subjects.id join shixuns on shixuns.id = stage_shixuns.shixun_id where
+                      subjects`.`hidden` = 0 AND `subjects`.`status` = 2 AND `subjects`.`name` like '%#{search}%'
+                      AND `subjects`.`repertoire_id` = #{select} GROUP BY subjects.id ORDER BY myshixun_member_count DESC")
       else
-        @subjects = Subject.find_by_sql("SELECT subjects.id, subjects.name, subjects.stages_count, subjects.repertoire_id, subjects.status,
-                            subjects.shixuns_count, COUNT(myshixuns.id) AS myshixun_member_count FROM myshixuns, stage_shixuns, subjects
-                            WHERE myshixuns.shixun_id = stage_shixuns.shixun_id AND stage_shixuns.subject_id = subjects.id
-                            AND `subjects`.`hidden` = 0 AND `subjects`.`status` = 2 AND `subjects`.`name` like '%#{search}%'
-                            GROUP BY subjects.id ORDER BY myshixun_member_count DESC")
+        @subjects = Subject.find_by_sql("SELECT subjects.id, subjects.user_id, subjects.name, subjects.stages_count, subjects.repertoire_id, subjects.status,
+                      subjects.shixuns_count, sum(shixuns.myshixuns_count) AS myshixun_member_count FROM subjects join stage_shixuns
+                      on stage_shixuns.subject_id = subjects.id join shixuns on shixuns.id = stage_shixuns.shixun_id where
+                      `subjects`.`hidden` = 0 AND `subjects`.`status` = 2 AND `subjects`.`name` like '%#{search}%'
+                      GROUP BY subjects.id ORDER BY myshixun_member_count DESC")
       end
     else
       # 我的路径
@@ -68,6 +68,8 @@ class SubjectsController < ApplicationController
       @subjects = @subjects.page(page).per(limit).includes(:shixuns)
     else
       @subjects = @subjects[offset, limit]
+      subject_ids = @subjects.pluck(:id)
+      @subjects = Subject.where(id: subject_ids).order("field(id,#{subject_ids.join(',')})").includes(:shixuns)
     end
   end
 

app/models/subject.rb

@@ -31,7 +31,7 @@ class Subject < ApplicationRecord
 
   # 挑战过路径的成员数
   def member_count
-    shixuns.sum(:myshixuns_count)
+    shixuns.pluck(:myshixuns_count).sum
   end
 
   def all_score