我已经在本地计算机上完成了简单的性能测试，这是python脚本：

import redis
import sqlite3
import time

data = {}
N = 100000

for i in xrange(N):
    key = "key-"+str(i)
    value = "value-"+str(i)
    data[key] = value

r = redis.Redis("localhost", db=1)
s = sqlite3.connect("testDB")
cs = s.cursor()

try:
    cs.execute("CREATE TABLE testTable(key VARCHAR(256), value TEXT)")
except Exception as excp:
    print str(excp)
    cs.execute("DROP TABLE testTable")
    cs.execute("CREATE TABLE testTable(key VARCHAR(256), value TEXT)")

print "[---Testing SQLITE---]"
sts = time.time()
for key in data:
    cs.execute("INSERT INTO testTable VALUES(?,?)", (key, data[key]))
    #s.commit()
s.commit()
ste = time.time()
print "[Total time of sql: %s]"%str(ste-sts)

print "[---Testing REDIS---]"
rts = time.time()
r.flushdb()# for empty db
for key in data:
    r.set(key, data[key])
rte = time.time()
print "[Total time of redis: %s]"%str(rte-rts)

我期望redis的执行速度更快，但是结果表明它的速度要慢得多：

[---Testing SQLITE---]
[Total time of sql: 0.615846157074]
[---Testing REDIS---]
[Total time of redis: 10.9668009281]

那么，redis是基于内存的，那么sqlite呢？为什么redis这么慢？什么时候需要使用Redis和什么时候需要使用sqlite？