find查询性能note

## 文档结构
{ 
    "_id" : ObjectId("5d1c5c8e5abba855bee7c734"), 
    "is_import" : NumberInt(2), 
    "flg_deleted" : NumberInt(0), 
    "job_number" : "2019094339", 
    "name" : "周老师1", 
    "sex" : "女", 
    "pwd" : "123456", 
    "course_name" : [ "语文",  "政治",  "音乐", "生物"], 
    "grade_class" : {"高一" : ["二班",   "三班" ]}, 
    "class_str" : "高一二班；高一三班；高二二班；高二三班；高二四班；高二九班", 
    "avatar_url" : "avatar/20190628172631741.jpg", 
    "avatar_s_url" : "avatar/20190628172631741.jpg"
}

## 运行代码
import time
from pymongo import MongoClient

db = MongoClient("192.168.0.192:27017").ctfs_admin

def change_type():
  ## t_test 总数：29495
  start_time1 = time.time()
  ## 对应的查询结果数量：3849
  result_list1 = db.t_test.find({'course_name': {'$regex':'物'}})
  time.sleep(1)
  start_time2 = time.time()
  debug(start_time2 - start_time1)
  
  start_time22 = time.time()
  ## 对应的查询结果数量：19937
  result_list2 = db.t_test.find({'class_str': {'$regex':'高一二班'}})
  time.sleep(1)
  start_time3 = time.time()
  debug(start_time3 - start_time22)


if __name__ == '__main__':
    change_type()

## 控制台输出
Wed Jul 03 16:13:18 - 1.000544786453247
Wed Jul 03 16:13:19 - 3849
Wed Jul 03 16:13:20 - 1.0005791187286377
Wed Jul 03 16:13:21 - 19937

总结：字符串相对列表来说，查询性能更优，数据存储结构偏向于字符串。
补充：excel导入5000条数据，for循环处理耗时约 0.055 s，批量插入 耗时约 0.515 s，而for循环逐条插入耗时约50s。
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