MongoDB 优化多个 find_one + insert inside 循环 [英] MongoDB optimize multiple find_one + insert inside loop
问题描述
我将 MongoDB 4.0.1 和 Pymongo 与 pyhton 3.5 一起使用.我必须每 30 - 60 秒循环超过 12000 个项目并将新数据添加到 MongoDB.在这个例子中,我们将讨论用户、宠物和汽车.用户可以获得 1 辆汽车和 1 只宠物.
I'm using MongoDB 4.0.1 and Pymongo with pyhton 3.5. I have to loop over 12000 items every 30 - 60 seconds and add new data into MongoDB. For this example we will talk about User, Pet and Car. The User can get 1 Car and 1 Pet.
我需要宠物 ObjectID 和汽车 ObjectID 来创建我的用户,所以我必须在循环中一一添加它们,这非常慢.查找现有数据并在数据不存在时添加它们大约需要 25 秒.
I need the pet ObjectID and the car ObjectID to create my User so I have to add them one by one in the loop and this is very slow. It takes ~25 seconds to find existing data and add them if the data not exist.
while dictionary != False:
# Create pet if not exist
existing_pet = pet.find_one({"code": dictionary['pet_code']})
if bool(existing_pet):
pet_id = existing_pet['_id']
else:
pet_id = pet.insert({
"code" : dictionary['pet_code'],
"name" : dictionary['name']
})
# Call web service to create pet remote
# Create car if not exist
existing_car = car.find_one({"platenumber": dictionary['platenumber']})
if bool(existing_car):
car_id = existing_car['_id']
else:
car_id = car.insert({
"platenumber" : dictionary['platenumber'],
"model" : dictionary['model'],
"energy" : 'electric'
})
# Call web service to create car remote
# Create user if not exist
existing_user = user.find_one(
{"$and": [
{"user_code": dictionary['user_code']},
{"car": car_id},
{"pet": pet_id}
]}
)
if not bool(existing_user):
user_data.append({
"pet" : pet_id,
"car" : car_id,
"firstname" : dictionary['firstname'],
"lastname" : dictionary['lastname']
})
# Call web service to create user remote
# Bulk insert user
if user_data:
user.insert_many(user_data)
我为用于 find_one 的每一列创建了索引:
I created indexes for each column used for the find_one :
db.user.createIndex( { user_code: 1 } )
db.user.createIndex( { pet: 1 } )
db.user.createIndex( { car: 1 } )
db.pet.createIndex( { pet_code: 1 }, { unique: true } )
db.car.createIndex( { platenumber: 1 }, { unique: true } )
有办法加速这个循环吗?有聚合或其他东西可以帮助我吗?或者也许是另一种方式来做我想做的事?
There is a way to speed up this loop ? There is something with aggregation or other things to help me ? Or maybe another way to do what I want ?
我愿意接受所有建议.
推荐答案
不要做 12000 次 find_one 查询,做 1 次查询以使用 $in 运算符将所有存在的内容都带回来.代码类似于:
Don´t do 12000 find_one queries, do 1 query to bring all that exist with $in operator. Code would be something like:
pet_codes = []
pet_names = []
while dictionary != False:
pet_codes.append(dictionary['pet_code'])
pet_names.append(dictionary['pet_name'])
pets = dict()
for pet in pet.find({"code": {$in: pet_codes}}):
pets[pet['code']] = pet
new_pets = []
for code, name in zip(pet_codes, pet_names):
if code not in pets:
new_pets.add({'pet_code': code, 'name': name})
pet.insert_many(new_pets)
由于您已经在 pet_code 上建立了唯一索引,因此我们可以做得更好:尝试将它们全部插入,因为如果我们尝试插入现有记录,该记录将出错,但其余的将通过使用成功文档:
As you already have an index on pet_code making it unique, we can do better: just try to insert them all, because if we try to insert an existing one that record will get an error, but the rest will succeed by using the ordered=False from the docs:
new_pets = []
while dictionary != False:
new_pets.add({
"code" : dictionary['pet_code'],
"name" : dictionary['name']
})
pet.insert_many(new_pets, ordered=False)
在没有唯一限制集的情况下,另一种方法是 批处理操作
In the case where you do not have a unique restriction set, another method is batching the operations
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