简单介绍redis以及ubuntu和windows下如何安装redis和配置文件详解

机缘巧合决定了解一下redis。

首先看个关于数据库的图，让想学数据库的同学有一个整体的概念。

好勒，下面说redis。

了解redis

Redis是一个开源，先进的key-value存储，并用于构建高性能，可扩展的Web应用程序的完美解决方案。
一句话概括就是：开源的/基于c语言的/基于内存亦可持久化的高性能的NoSql的键值对数据库。

redis存储结构丰富：字符串类型、散列类型、列表类型、集合类型、有序集合类型。

内存存储与持久化：1秒写入10万键值对、异步写入硬盘

功能丰富：用作数据库、缓存系统、队列

简单稳定：使用命令来读取数据，redis命令比sql语言简单的多
比如我们在post表中查询一个id 为1的学生SQL语句这写：

select title from post where id=1 ;

redis语句只需要一句即可：

HGET post:1 title

---

了解完毕我们来安装一下，很简单。

首先ubuntu下安装redis

1、打开终端，输入一下命令

$sudo apt-get update$sudo apt-get install redis-server

确认安装。等待安装完成。

2、启动redis。

$redis-server

3、检查Redis是否在工作

$redis-cli

上面的提示127.0.0.1是本机的IP地址，6379为Redis服务器运行的端口。现在输入PING命令，回复pong这说明你已经成功地安装Redis在您的机器上。

Windows下安装redis

1、下载地址：https://github.com/dmajkic/redis/downloads。下载windows版本的redis包。最新的是双版本，32、64位都在一起。

2、下载后解压到自己的某个文件夹。我选择64位的并把让它放在：E:\redis\64bit。在文件夹中可执行的2进制文件共有5个，分别代表如下：

3、打开一个cmd窗口 使用cd命令切换目录到E:\redis\64bit 运行 redis-server.exe redis.conf

4、出现上面那个图就表示启动服务成功了，这时候别启一个cmd窗口，原来的不要关闭，不然就无法访问服务端了。

5、切换到redis目录下运行 redis-cli.exe -h 127.0.0.1 -p 6379 出现下图：

我们可以输入一个简单的测试数据测试。
当我们访问服务端时，我们观察刚刚开启的服务端能看到如下数据。

这时候，就已经完成配置了，现在说下它的的redis.conf配置文件。我摘抄了一个详细的说明，留博客备查

下面是配置相关项的说明

# Redis configuration file example  # Note on units: when memory size is needed, it is possible to specifiy  # it in the usual form of 1k 5GB 4M and so forth:  #  # 1k => 1000 bytes  # 1kb => 1024 bytes  # 1m => 1000000 bytes  # 1mb => 1024*1024 bytes  # 1g => 1000000000 bytes  # 1gb => 1024*1024*1024 bytes  #  # units are case insensitive so 1GB 1Gb 1gB are all the same.  # 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    Redis默认不是以守护进程的方式运行，可以通过该配置项修改，使用yes启用守护进程  # When running daemonized, Redis writes a pid file in /var/run/redis.pid by  # default. You can specify a custom pid file location here.  pidfile /var/run/redis.pid  当Redis以守护进程方式运行时，Redis默认会把pid写入/var/run/redis.pid文件，可以通过pidfile指定  # Accept connections on the specified port, default is 6379.  # If port 0 is specified Redis will not listen on a TCP socket.  port 6379  指定Redis监听端口，默认端口为6379  # If you want you can bind a single interface, if the bind option is not  # specified all the interfaces will listen for incoming connections.  #  # bind 127.0.0.1  绑定的主机地址  # Specify the path for the unix socket that will be used to listen for  # incoming connections. There is no default, so Redis will not listen  # on a unix socket when not specified.  #  # unixsocket /tmp/redis.sock  # unixsocketperm 755  # Close the connection after a client is idle for N seconds (0 to disable)  timeout 0  当 客户端闲置多长时间后关闭连接，如果指定为0，表示关闭该功能  # Set server verbosity to 'debug'  # it can be one of:  # debug (a lot of information, useful for development/testing)  # verbose (many rarely useful info, but not a mess like the debug level)  # notice (moderately verbose, what you want in production probably)  # warning (only very important / critical messages are logged)  loglevel verbose  指定日志记录级别，Redis总共支持四个级别：debug、verbose、notice、warning，默认为verbose  # Specify the log file name. Also 'stdout' can be used to force  # Redis 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  日志记录方式，默认为标准输出，如果配置Redis为守护进程方式运行，而这里又配置为日志记录方式为标准输出，则日志将会发送给/dev/null  # To enable logging to the system logger, just set 'syslog-enabled' to yes,  # and optionally update the other syslog parameters to suit your needs.  # syslog-enabled no  # Specify the syslog identity.  # syslog-ident redis  # Specify the syslog facility.  Must be USER or between LOCAL0-LOCAL7.  # syslog-facility local0  # 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  设置数据库的数量，默认数据库为0，可以使用SELECT <dbid>命令在连接上指定数据库id  ################################ 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  #  #   Note: you can disable saving at all commenting all the "save" lines.  save 900 1  save 300 10  save 60 10000  分别表示900秒（15分钟）内有1个更改，300秒（5分钟）内有10个更改以及60秒内有10000个更改。  指定在多长时间内，有多少次更新操作，就将数据同步到数据文件，可以多个条件配合  # 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  指定存储至本地数据库时是否压缩数据，默认为yes，Redis采用LZF压缩，如果为了节省CPU时间，可以关闭该选项，但会导致数据库文件变的巨大  # The filename where to dump the DB  dbfilename dump.rdb  指定本地数据库文件名，默认值为dump.rdb  # The working directory.  #  # The DB will be written inside this directory, with the filename specified  # above using the 'dbfilename' configuration directive.  #   # Also the Append Only File will be created inside this directory.  #   # Note that you must specify a directory here, not a file name.  dir ./  指定本地数据库存放目录  ################################# 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>  slaveof <masterip> <masterport> 设置当本机为slav服务时，设置master服务的IP地址及端口，在Redis启动时，它会自动从master进行数据同步  # 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>  masterauth <master-password> 当master服务设置了密码保护时，slav服务连接master的密码  # When a slave lost the connection with the master, or when the replication  # is still in progress, the slave can act in two different ways:  #  # 1) if slave-serve-stale-data is set to 'yes' (the default) the slave will  #    still reply to client requests, possibly with out of data data, or the  #    data set may just be empty if this is the first synchronization.  #  # 2) if slave-serve-stale data is set to 'no' the slave will reply with  #    an error "SYNC with master in progress" to all the kind of commands  #    but to INFO and SLAVEOF.  #  slave-serve-stale-data yes  # Slaves send PINGs to server in a predefined interval. It's possible to change  # this interval with the repl_ping_slave_period option. The default value is 10  # seconds.  #  # repl-ping-slave-period 10  # The following option sets a timeout for both Bulk transfer I/O timeout and  # master data or ping response timeout. The default value is 60 seconds.  #  # It is important to make sure that this value is greater than the value  # specified for repl-ping-slave-period otherwise a timeout will be detected  # every time there is low traffic between the master and the slave.  #  # repl-timeout 60  ################################## 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).  #   # Warning: since Redis is pretty fast an outside user can try up to  # 150k passwords per second against a good box. This means that you should  # use a very strong password otherwise it will be very easy to break.  #  # requirepass foobared   requirepass foobared 设置Redis连接密码，如果配置了连接密码，客户端在连接Redis时需要通过AUTH <password>命令提供密码，默认关闭  # Command renaming.  #  # It is possilbe to change the name of dangerous commands in a shared  # environment. For instance the CONFIG command may be renamed into something  # of hard to guess so that it will be still available for internal-use  # tools but not available for general clients.  #  # Example:  #  # rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52  #  # It is also possilbe to completely kill a command renaming it into  # an empty string:  #  # rename-command CONFIG ""  ################################### 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 limits.  # Once the limit is reached Redis will close all the new connections sending  # an error 'max number of clients reached'.  #  # maxclients 128  maxclients 128 设置同一时间最大客户端连接数，默认无限制，Redis可以同时打开的客户端连接数为Redis进程可以打开的最大文件描述符数，如果设置 maxclients 0，表示不作限制。当客户端连接数到达限制时，Redis会关闭新的连接并向客户端返回max number of clients reached错误信息  # 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>   maxmemory <bytes>指定Redis最大内存限制，Redis在启动时会把数据加载到内存中，达到最大内存后，Redis会先尝试清除已到期或即将到期的Key，当此方法处理 后，仍然到达最大内存设置，将无法再进行写入操作，但仍然可以进行读取操作。Redis新的vm机制，会把Key存放内存，Value会存放在swap区  # MAXMEMORY POLICY: how Redis will select what to remove when maxmemory  # is reached? You can select among five behavior:  #   # volatile-lru -> remove the key with an expire set using an LRU algorithm  # allkeys-lru -> remove any key accordingly to the LRU algorithm  # volatile-random -> remove a random key with an expire set  # allkeys->random -> remove a random key, any key  # volatile-ttl -> remove the key with the nearest expire time (minor TTL)  # noeviction -> don't expire at all, just return an error on write operations  #   # Note: with all the kind of policies, Redis will return an error on write  #       operations, when there are not suitable keys for eviction.  #  #       At the date of writing this commands are: set setnx setex append  #       incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd  #       sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby  #       zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby  #       getset mset msetnx exec sort  #  # The default is:  #  # maxmemory-policy volatile-lru  # LRU and minimal TTL algorithms are not precise algorithms but approximated  # algorithms (in order to save memory), so you can select as well the sample  # size to check. For instance for default Redis will check three keys and  # pick the one that was used less recently, you can change the sample size  # using the following configuration directive.  #  # maxmemory-samples 3  ############################## 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.aof. 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.  #  # IMPORTANT: Check the BGREWRITEAOF to check how to rewrite the append  # log file in background when it gets too big.  appendonly no  appendonly no指定是否在每次更新操作后进行日志记录，Redis在默认情况下是异步的把数据写入磁盘，如果不开启，可能会在断电时导致一段时间内的数据丢失。因为 redis本身同步数据文件是按上面save条件来同步的，所以有的数据会在一段时间内只存在于内存中。默认为no  # The name of the append only file (default: "appendonly.aof")  # appendfilename appendonly.aof   appendfilename appendonly.aof指定更新日志文件名，默认为appendonly.aof  # 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 "everysec" that's usually the right compromise between  # speed and data safety. It's up to you to understand if you can relax this to  # "no" that will will let the operating system flush the output buffer when  # it wants, for better performances (but if you can live with the idea of  # some data loss consider the default persistence mode that's snapshotting),  # or on the contrary, use "always" that's very slow but a bit safer than  # everysec.  #  # If unsure, use "everysec".  # appendfsync always  appendfsync everysec  # appendfsync no  指定更新日志条件，共有3个可选值：  no：表示等操作系统进行数据缓存同步到磁盘（快）  always：表示每次更新操作后手动调用fsync()将数据写到磁盘（慢，安全）  everysec：表示每秒同步一次（折衷，默认值）  # When the AOF fsync policy is set to always or everysec, and a background  # saving process (a background save or AOF log background rewriting) is  # performing a lot of I/O against the disk, in some Linux configurations  # Redis may block too long on the fsync() call. Note that there is no fix for  # this currently, as even performing fsync in a different thread will block  # our synchronous write(2) call.  #  # In order to mitigate this problem it's possible to use the following option  # that will prevent fsync() from being called in the main process while a  # BGSAVE or BGREWRITEAOF is in progress.  #  # This means that while another child is saving the durability of Redis is  # the same as "appendfsync none", that in pratical terms means that it is  # possible to lost up to 30 seconds of log in the worst scenario (with the  # default Linux settings).  #   # If you have latency problems turn this to "yes". Otherwise leave it as  # "no" that is the safest pick from the point of view of durability.  no-appendfsync-on-rewrite no  # Automatic rewrite of the append only file.  # Redis is able to automatically rewrite the log file implicitly calling  # BGREWRITEAOF when the AOF log size will growth by the specified percentage.  #   # This is how it works: Redis remembers the size of the AOF file after the  # latest rewrite (or if no rewrite happened since the restart, the size of  # the AOF at startup is used).  #  # This base size is compared to the current size. If the current size is  # bigger than the specified percentage, the rewrite is triggered. Also  # you need to specify a minimal size for the AOF file to be rewritten, this  # is useful to avoid rewriting the AOF file even if the percentage increase  # is reached but it is still pretty small.  #  # Specify a precentage of zero in order to disable the automatic AOF  # rewrite feature.  auto-aof-rewrite-percentage 100  auto-aof-rewrite-min-size 64mb  ################################## SLOW LOG ###################################  # The Redis Slow Log is a system to log queries that exceeded a specified  # execution time. The execution time does not include the I/O operations  # like talking with the client, sending the reply and so forth,  # but just the time needed to actually execute the command (this is the only  # stage of command execution where the thread is blocked and can not serve  # other requests in the meantime).  #   # You can configure the slow log with two parameters: one tells Redis  # what is the execution time, in microseconds, to exceed in order for the  # command to get logged, and the other parameter is the length of the  # slow log. When a new command is logged the oldest one is removed from the  # queue of logged commands.  # The following time is expressed in microseconds, so 1000000 is equivalent  # to one second. Note that a negative number disables the slow log, while  # a value of zero forces the logging of every command.  slowlog-log-slower-than 10000  # There is no limit to this length. Just be aware that it will consume memory.  # You can reclaim memory used by the slow log with SLOWLOG RESET.  slowlog-max-len 1024  ################################ VIRTUAL MEMORY ###############################  ### WARNING! Virtual Memory is deprecated in Redis 2.4  ### The use of Virtual Memory is strongly discouraged.  ### WARNING! Virtual Memory is deprecated in Redis 2.4  ### The use of Virtual Memory is strongly discouraged.  # Virtual Memory allows Redis to work with datasets bigger than the actual  # amount of RAM needed to hold the whole dataset in memory.  # In order to do so very used keys are taken in memory while the other keys  # are swapped into a swap file, similarly to what operating systems do  # with memory pages.  #  # To enable VM just set 'vm-enabled' to yes, and set the following three  # VM parameters accordingly to your needs.  vm-enabled no  指定是否启用虚拟内存机制，默认值为no，简单的介绍一下，VM机制将数据分页存放，由Redis将访问量较少的页即冷数据swap到磁盘上，访问多的页面由磁盘自动换出到内存中（在后面的文章我会仔细分析Redis的VM机制）  # vm-enabled yes  # This is the path of the Redis swap file. As you can guess, swap files  # can't be shared by different Redis instances, so make sure to use a swap  # file for every redis process you are running. Redis will complain if the  # swap file is already in use.  #  # The best kind of storage for the Redis swap file (that's accessed at random)   # is a Solid State Disk (SSD).  #  # *** WARNING *** if you are using a shared hosting the default of putting  # the swap file under /tmp is not secure. Create a dir with access granted  # only to Redis user and configure Redis to create the swap file there.  vm-swap-file /tmp/redis.swap  虚拟内存文件路径，默认值为/tmp/redis.swap，不可多个Redis实例共享  # vm-max-memory configures the VM to use at max the specified amount of  # RAM. Everything that deos not fit will be swapped on disk *if* possible, that  # is, if there is still enough contiguous space in the swap file.  #  # With vm-max-memory 0 the system will swap everything it can. Not a good  # default, just specify the max amount of RAM you can in bytes, but it's  # better to leave some margin. For instance specify an amount of RAM  # that's more or less between 60 and 80% of your free RAM.  vm-max-memory 0  将所有大于vm-max-memory的数据存入虚拟内存,无论vm-max-memory设置多小,所有索引数据都是内存存储的(Redis的索引数据 就是keys),也就是说,当vm-max-memory设置为0的时候,其实是所有value都存在于磁盘。默认值为0  # Redis swap files is split into pages. An object can be saved using multiple  # contiguous pages, but pages can't be shared between different objects.  # So if your page is too big, small objects swapped out on disk will waste  # a lot of space. If you page is too small, there is less space in the swap  # file (assuming you configured the same number of total swap file pages).  #  # If you use a lot of small objects, use a page size of 64 or 32 bytes.  # If you use a lot of big objects, use a bigger page size.  # If unsure, use the default :)  vm-page-size 32  Redis swap文件分成了很多的page，一个对象可以保存在多个page上面，但一个page上不能被多个对象共享，vm-page-size是要根据存储的 数据大小来设定的，作者建议如果存储很多小对象，page大小最好设置为32或者64bytes；如果存储很大大对象，则可以使用更大的page，如果不 确定，就使用默认值  # Number of total memory pages in the swap file.  # Given that the page table (a bitmap of free/used pages) is taken in memory,  # every 8 pages on disk will consume 1 byte of RAM.  #  # The total swap size is vm-page-size * vm-pages  #  # With the default of 32-bytes memory pages and 134217728 pages Redis will  # use a 4 GB swap file, that will use 16 MB of RAM for the page table.  #  # It's better to use the smallest acceptable value for your application,  # but the default is large in order to work in most conditions.  vm-pages 134217728  设置swap文件中的page数量，由于页表（一种表示页面空闲或使用的bitmap）是在放在内存中的，，在磁盘上每8个pages将消耗1byte的内存。  # Max number of VM I/O threads running at the same time.  # This threads are used to read/write data from/to swap file, since they  # also encode and decode objects from disk to memory or the reverse, a bigger  # number of threads can help with big objects even if they can't help with  # I/O itself as the physical device may not be able to couple with many  # reads/writes operations at the same time.  #  # The special value of 0 turn off threaded I/O and enables the blocking  # Virtual Memory implementation.  vm-max-threads 4  设置访问swap文件的线程数,最好不要超过机器的核数,如果设置为0,那么所有对swap文件的操作都是串行的，可能会造成比较长时间的延迟。默认值为4  ############################### ADVANCED CONFIG ###############################  # Hashes are encoded in a special way (much more memory efficient) when they  # have at max a given numer of elements, and the biggest element does not  # exceed a given threshold. You can configure this limits with the following  # configuration directives.  hash-max-zipmap-entries 512  hash-max-zipmap-value 64  指定在超过一定的数量或者最大的元素超过某一临界值时，采用一种特殊的哈希算法  # Similarly to hashes, small lists are also encoded in a special way in order  # to save a lot of space. The special representation is only used when  # you are under the following limits:  list-max-ziplist-entries 512  list-max-ziplist-value 64  # Sets have a special encoding in just one case: when a set is composed  # of just strings that happens to be integers in radix 10 in the range  # of 64 bit signed integers.  # The following configuration setting sets the limit in the size of the  # set in order to use this special memory saving encoding.  set-max-intset-entries 512  # Similarly to hashes and lists, sorted sets are also specially encoded in  # order to save a lot of space. This encoding is only used when the length and  # elements of a sorted set are below the following limits:  zset-max-ziplist-entries 128  zset-max-ziplist-value 64  # Active rehashing uses 1 millisecond every 100 milliseconds of CPU time in  # order to help rehashing the main Redis hash table (the one mapping top-level  # keys to values). The hash table implementation redis uses (see dict.c)  # performs a lazy rehashing: the more operation you run into an hash table  # that is rhashing, the more rehashing "steps" are performed, so if the  # server is idle the rehashing is never complete and some more memory is used  # by the hash table.  #   # The default is to use this millisecond 10 times every second in order to  # active rehashing the main dictionaries, freeing memory when possible.  #  # If unsure:  # use "activerehashing no" if you have hard latency requirements and it is  # not a good thing in your environment that Redis can reply form time to time  # to queries with 2 milliseconds delay.  #  # use "activerehashing yes" if you don't have such hard requirements but  # want to free memory asap when possible.  activerehashing yes  ################################## INCLUDES ###################################  # Include one or more other config files here.  This is useful if you  # have a standard template that goes to all redis server but also need  # to customize a few per-server settings.  Include files can include  # other files, so use this wisely.  #  # include /path/to/local.conf  # include /path/to/other.conf