验证MongoDB中$set、$inc、$push几种修改器操作的速度

在MongoDB中，$set、$inc、$push都能够对数据库进行操作，那么到底哪种修改器操作速度更快呢？我们今天来验证一下。

先描述一下本人的实验环境：

Win8操作系统64位，内装虚拟机32位系统，CentOS5.5

实验第一步，安装并启动MongoDB数据库服务器：

[plain] 
[root@h3 home]# mongod -f /etc/mongod.conf  
Thu Jul 25 00:19:15.950  
Thu Jul 25 00:19:15.950 warning: 32-bit servers don't have journaling enabled by default. Please use --journal if you want durability.  
Thu Jul 25 00:19:15.950  
about to fork child process, waiting until server is ready for connections.  
forked process: 14519  
all output going to: /var/log/mongo/mongod.log  
child process started successfully, parent exiting  
[root@h3 home]#

实验第二步，编辑测试文件，这里我们保存为test.py，文件内容如下：

[plain] 
#!usr/bin/python  
#coding=utf-8  
  
from pymongo import Connection  
import time  
db = Connection().performance_test  
db.drop_collection("updates")  
collection = db.updates  
collection.insert({"x": 1})  
  
collection.find_one()  
  
# in inc test  
start_inc = time.time()  
for i in range(100000):  
    collection.update({}, {"$inc" : {"x" : 1}})  
collection.find_one()  
print '$inc:', time.time() - start_inc  
  
# in set  test  
start_set = time.time()  
for i in range(100000):  
    collection.update({}, {"$set" : {"x" : 1}})  
collection.find_one()  
print '$set:', time.time() - start_set  
  
# in push test  
start_push = time.time()  
for i in range(100000):  
    collection.update({}, {"$push" : {"x" : 1}})  
collection.find_one()  
print '$push:', time.time() - start_push

实验第三步，我们运行测试test.py，这里我们运行5次

[plain] 
[root@h3 home]# python test.py  
$inc: 6.83732295036  
$set: 6.61989808083  
$push: 10.5028648376  
[root@h3 home]# python test.py  
$inc: 6.56225991249  
$set: 6.12179207802  
$push: 10.264081955  
[root@h3 home]# python test.py  
$inc: 6.18113183975  
$set: 6.4468960762  
$push: 10.077311039  
[root@h3 home]# python test.py  
$inc: 6.19089698792  
$set: 6.61814904213  
$push: 9.5483288765  
[root@h3 home]# python test.py  
$inc: 6.93615078926  
$set: 6.58752202988  
$push: 9.91513586044  
[root@h3 home]#

结论：在MongoDB中，$inc、$set 修改器的操作速度相差不大，但明显快于$push修改器。