Python Pymongo中Connection()与MongoClient()差异

在git找了几个blog的源码，在学习的过程中，发现有人使用Connection()，有人却在使用MongoClient()，那么到底两者有什么差别呢？

且看分析如下：

db = Connection('192.168.1.101', 27017).performance_test

#client = MongoClient('192.168.1.101', 27017)

#db = client.performance_test 

 db.drop_collection("updates") 

collection = db.updates 

collection.insert({"x": 1}) 

collection.find_one() 

start = time.time() 

for i in range(100000): 

        collection.update({}, {"$push" : {"x" : 1}}) 

...

运行结果：

>python test_mongo_conn.py

8.43799996376

>python test_mongo_client.py

62.5780000687

用Connection() 8秒，MongoClient()则花了62秒，这性能相差也太多了。

很是疑惑，于是查了pymongo的文档，原来两者有个选项的默认行为不同：

class pymongo.connection.Connection([host='localhost'[, port=27017[, max_pool_size=10[, network_timeout=None[, document_class=dict[, tz_aware=False[, **kwargs]]]]]]])

Write Concern options:

safe: Connection disables acknowledgement of write operations. Use safe=True to enable write acknowledgement.

w: (integer or string) If this is a replica set, write operations will block until they have been replicated to the specified number or tagged set of servers. w=<int> always includes the replica set primary (e.g. w=3 means write to the primary and wait until replicated to two secondaries). Implies safe=True.

wtimeout: (integer) Used in conjunction with w. Specify a value in milliseconds to control how long to wait for write propagation to complete. If replication does not complete in the given timeframe, a timeout exception is raised. Implies safe=True.

j: If True block until write operations have been committed to the journal. Ignored if the server is running without journaling. Implies safe=True.

fsync: If True force the database to fsync all files before returning. When used with j the server awaits the next group commit before returning. Implies safe=True.

safe选项决定操作是“瞬时完成”与“安全操作”，connection()默认是safe=False,即瞬时完成，不等服务器回应，而MongoClient()默认是safe=True，即安全操作，等服务器确认后才继续下一步操作。

所以一个8秒，一个62秒，这个差距实际上是“瞬时完成”与“安全操作”两者的性能差别。

当将Connection() 和MongoClient()建立连接时指定相同的safe参数，两者的性能表现是一样的。

client = MongoClient('192.168.1.101', 27017,safe=False)

#db = Connection('192.168.1.101', 27017,safe=False).performance_test

结论：Python用Connection()连接时，修改操作速度非常快，而用MongoClient()建立的连接，操作速度慢很多。

顺便分享账号密码登录的代码：

from pymongo import MongoClient

client = MongoClient('www.yeayee.com','')

client.database.authenticate("user","password")

db = client.database

collection = db.collection

巴特西

Python Pymongo中Connection()与MongoClient()差异

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