redis是一個key-value存儲係統.和Memcached類似,它支持存儲的value類型相對更多,包括string(字符串)、list(鏈表)、set(集合)、zset(sorted set --有序集合)和hashs(哈希類型).這些數據類型都支持push/pop、add/remove及取交集並集和差集及更豐富的操作,而且這些操作都是原子性的.在此基礎上,redis支持各種不同方式的排序.與memcached一樣,為了保證效率,數據都是緩存在內存中.區別的是redis會周期性的把更新的數據寫入磁盤或者把修改操作寫入追加的記錄文件,並且在此基礎上實現了master-slave(主從)同步.
性能極高 – Redis能支持超過 100K+ 每秒的讀寫頻率。
豐富的數據類型 – Redis支持二進製案例的 Strings, Lists, Hashes, Sets 及 Ordered Sets 數據類型操作。
原子 – Redis的所有操作都是原子性的,同時Redis還支持對幾個操作全並後的原子性執行。
豐富的特性 – Redis還支持 publish/subscribe, 通知, key 過期等等特性。
下麵是官方的bench-mark數據:
測試完成了50個並發執行100000個請求。
設置和獲取的值是一個256字節字符串。
Linux box是運行Linux 2.6,這是X3320 Xeon 2.5 ghz。
文本執行使用loopback接口(127.0.0.1)。
結果:寫的速度是110000次/s,讀的速度是81000次/s 。
就DB來說,Redis成績已經很驚人了,且不說memcachedb和tokyocabinet之流,就說原版的memcached,速度似乎也隻能達到這個級別。Redis根本是使用內存存儲,持久化的關鍵是這三條指令:SAVE BGSAVE LASTSAVE .
當接收到SAVE指令的時候,Redis就會dump數據到一個文件裏麵。值得一說的是它的獨家功能:存儲列表和集合,這是它與mc之流相比更有競爭力的地方。
不介紹mc裏麵已經有的東東,隻列出特殊的:
TYPE key — 用來獲取某key的類型
KEYS pattern — 匹配所有符合模式的key,比如KEYS * 就列出所有的key了,當然,複雜度O(n)
RANDOMKEY - 返回隨機的一個key
RENAME oldkeynewkey— key也可以改名
列表操作,精華
RPUSH key string — 將某個值加入到一個key列表頭部
LPUSH key string — 將某個值加入到一個key列表末尾
LLEN key — 列表長度
LRANGE key start end — 返回列表中某個範圍的值,相當於mysql裏麵的分頁查詢那樣
LTRIM key start end — 隻保留列表中某個範圍的值
LINDEX key index — 獲取列表中特定索引號的值,要注意是O(n)複雜度
LSET key index value — 設置列表中某個位置的值
LPOP key
RPOP key — 和上麵的LPOP一樣,就是類似棧或隊列的那種取頭取尾指令,可以當成消息隊列來使用了
集合操作
SADD key member — 增加元素
SREM key member — 刪除元素
SCARD key — 返回集合大小
SISMEMBER key member — 判斷某個值是否在集合中
SINTER key1 key2 ... keyN — 獲取多個集合的交集元素
SMEMBERS key — 列出集合的所有元素
還有Multiple DB的命令,可以更換db,數據可以隔離開,默認是存放在DB 0
可以在Windows下進行安裝
Redis安裝文件解壓後,有以下幾個文件。見下圖
redis-server.exe:服務程序
redis-check-dump.exe:本地數據庫檢查
redis-check-aof.exe:更新日誌檢查
redis-benchmark.exe:性能測試,用以模擬同時由N個客戶端發送M個 SETs/GETs 查詢 (類似於 Apache 的ab 工具).
在解壓好redis的安裝文件到E:\根目錄後,還需要在redis根目錄增加一個redis的配置文件redis.conf,文件具體內容附件中有,不過這裏我仍然把配置文件的內容貼上來:
# Redis configuration file example
# By default Redis does not run as a daemon. Use 'yes' if you need it.
# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
daemonize no
# When run as a daemon, Redis write a pid file in /var/run/redis.pid by default.
# You can specify a custom pid file location here.
pidfile /var/run/redis.pid
# Accept connections on the specified port, default is 6379
port 6379
# If you want you can bind a single interface, if the bind option is not
# specified all the interfaces will listen for connections.
#
# bind 127.0.0.1
# Close the connection after a client is idle for N seconds (0 to disable)
timeout 300
# Set server verbosity to 'debug'
# it can be one of:
# debug (a lot of information, useful for development/testing)
# notice (moderately verbose, what you want in production probably)
# warning (only very important / critical messages are logged)
loglevel debug
# Specify the log file name. Also 'stdout' can be used to force
# the demon to log on the standard output. Note that if you use standard
# output for logging but daemonize, logs will be sent to /dev/null
logfile stdout
# Set the number of databases. The default database is DB 0, you can select
# a different one on a per-connection basis using SELECT <dbid> where
# dbid is a number between 0 and 'databases'-1
databases 16
################################ SNAPSHOTTING #################################
#
# Save the DB on disk:
#
# save <seconds> <changes>
#
# Will save the DB if both the given number of seconds and the given
# number of write operations against the DB occurred.
#
# In the example below the behaviour will be to save:
# after 900 sec (15 min) if at least 1 key changed
# after 300 sec (5 min) if at least 10 keys changed
# after 60 sec if at least 10000 keys changed
save 900 1
save 300 10
save 60 10000
# Compress string objects using LZF when dump .rdb databases?
# For default that's set to 'yes' as it's almost always a win.
# If you want to save some CPU in the saving child set it to 'no' but
# the dataset will likely be bigger if you have compressible values or keys.
rdbcompression yes
# The filename where to dump the DB
dbfilename dump.rdb
# For default save/load DB in/from the working directory
# Note that you must specify a directory not a file name.
dir ./
################################# REPLICATION #################################
# Master-Slave replication. Use slaveof to make a Redis instance a copy of
# another Redis server. Note that the configuration is local to the slave
# so for example it is possible to configure the slave to save the DB with a
# different interval, or to listen to another port, and so on.
#
# slaveof <masterip> <masterport>
# If the master is password protected (using the "requirepass" configuration
# directive below) it is possible to tell the slave to authenticate before
# starting the replication synchronization process, otherwise the master will
# refuse the slave request.
#
# masterauth <master-password>
################################## SECURITY ###################################
# Require clients to issue AUTH <PASSWORD> before processing any other
# commands. This might be useful in environments in which you do not trust
# others with access to the host running redis-server.
#
# This should stay commented out for backward compatibility and because most
# people do not need auth (e.g. they run their own servers).
#
# requirepass foobared
################################### LIMITS ####################################
# Set the max number of connected clients at the same time. By default there
# is no limit, and it's up to the number of file descriptors the Redis process
# is able to open. The special value '0' means no limts.
# Once the limit is reached Redis will close all the new connections sending
# an error 'max number of clients reached'.
#
# maxclients 128
# Don't use more memory than the specified amount of bytes.
# When the memory limit is reached Redis will try to remove keys with an
# EXPIRE set. It will try to start freeing keys that are going to expire
# in little time and preserve keys with a longer time to live.
# Redis will also try to remove objects from free lists if possible.
#
# If all this fails, Redis will start to reply with errors to commands
# that will use more memory, like SET, LPUSH, and so on, and will continue
# to reply to most read-only commands like GET.
#
# WARNING: maxmemory can be a good idea mainly if you want to use Redis as a
# 'state' server or cache, not as a real DB. When Redis is used as a real
# database the memory usage will grow over the weeks, it will be obvious if
# it is going to use too much memory in the long run, and you'll have the time
# to upgrade. With maxmemory after the limit is reached you'll start to get
# errors for write operations, and this may even lead to DB inconsistency.
#
# maxmemory <bytes>
############################## APPEND ONLY MODE ###############################
# By default Redis asynchronously dumps the dataset on disk. If you can live
# with the idea that the latest records will be lost if something like a crash
# happens this is the preferred way to run Redis. If instead you care a lot
# about your data and don't want to that a single record can get lost you should
# enable the append only mode: when this mode is enabled Redis will append
# every write operation received in the file appendonly.log. This file will
# be read on startup in order to rebuild the full dataset in memory.
#
# Note that you can have both the async dumps and the append only file if you
# like (you have to comment the "save" statements above to disable the dumps).
# Still if append only mode is enabled Redis will load the data from the
# log file at startup ignoring the dump.rdb file.
#
# The name of the append only file is "appendonly.log"
#
# IMPORTANT: Check the BGREWRITEAOF to check how to rewrite the append
# log file in background when it gets too big.
appendonly no
# The fsync() call tells the Operating System to actually write data on disk
# instead to wait for more data in the output buffer. Some OS will really flush
# data on disk, some other OS will just try to do it ASAP.
#
# Redis supports three different modes:
#
# no: don't fsync, just let the OS flush the data when it wants. Faster.
# always: fsync after every write to the append only log . Slow, Safest.
# everysec: fsync only if one second passed since the last fsync. Compromise.
#
# The default is "always" that's the safer of the options. It's up to you to
# understand if you can relax this to "everysec" that will fsync every second
# or to "no" that will let the operating system flush the output buffer when
# it want, for better performances (but if you can live with the idea of
# some data loss consider the default persistence mode that's snapshotting).
appendfsync always
# appendfsync everysec
# appendfsync no
############################### ADVANCED CONFIG ###############################
# Glue small output buffers together in order to send small replies in a
# single TCP packet. Uses a bit more CPU but most of the times it is a win
# in terms of number of queries per second. Use 'yes' if unsure.
glueoutputbuf yes
# Use object sharing. Can save a lot of memory if you have many common
# string in your dataset, but performs lookups against the shared objects
# pool so it uses more CPU and can be a bit slower. Usually it's a good
# idea.
#
# When object sharing is enabled (shareobjects yes) you can use
# shareobjectspoolsize to control the size of the pool used in order to try
# object sharing. A bigger pool size will lead to better sharing capabilities.
# In general you want this value to be at least the double of the number of
# very common strings you have in your dataset.
#
# WARNING: object sharing is experimental, don't enable this feature
# in production before of Redis 1.0-stable. Still please try this feature in
# your development environment so that we can test it better.
# shareobjects no
# shareobjectspoolsize 1024
將附件中的redis_conf.rar解壓下來放到redis的根目錄中即可。到此,redis的安裝已經完畢。下麵開始使用redis數據庫。
啟動redis:
輸入命令:redis-server.exe redis.conf
啟動後如下圖所示:
啟動cmd窗口要一直開著,關閉後則Redis服務關閉。
這時服務開啟著,另外開一個窗口進行,設置客戶端:
輸入命令:redis-cli.exe -h 202.117.16.133 -p 6379
輸入後如下圖所示:
然後可以開始玩了:
設置一個Key並獲取返回的值:
$ ./redis-cli set mykey somevalue
OK
$ ./redis-cli get mykey
Somevalue
如何添加值到list:
$ ./redis-cli lpush mylist firstvalue
OK
$ ./redis-cli lpush mylist secondvalue
OK
$ ./redis-cli lpush mylist thirdvalue
OK
$ ./redis-cli lrange mylist 0 -1
. thirdvalue
. secondvalue
. firstvalue
$ ./redis-cli rpop mylist
firstvalue
$ ./redis-cli lrange mylist 0 -1
. thirdvalue
. secondvalue
redis-benchmark.exe:性能測試,用以模擬同時由N個客戶端發送M個 SETs/GETs 查詢 (類似於 Apache 的 ab 工具).
./redis-benchmark -n 100000 –c 50
====== SET ======
100007 requests completed in 0.88 seconds (譯者注:100004 查詢完成於 1.14 秒 )
50 parallel clients (譯者注:50個並發客戶端)
3 bytes payload (譯者注:3字節有效載荷)
keep alive: 1 (譯者注:保持1個連接)
58.50% <= 0 milliseconds(譯者注:毫秒)
99.17% <= 1 milliseconds
99.58% <= 2 milliseconds
99.85% <= 3 milliseconds
99.90% <= 6 milliseconds
100.00% <= 9 milliseconds
114293.71 requests per second(譯者注:每秒 114293.71 次查詢)
Windows下測試並發客戶端極限為60
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