NoSQL的一些碎碎念 NoSQL并不像字面意思那样，并不是说不再使用SQL，不再使用关系数据库，他真正的意思是Not Only SQL，他的出现是为了弥补关系数据库的不足，尤其是是在处理超大量的数据时。NoSQL并不是一个数据库的名字，而是一系列不再局限于关系型的数据
NoSQL的一些碎碎念
NoSQL并不像字面意思那样，并不是说不再使用SQL，不再使用关系数据库，他真正的意思是Not Only SQL，他的出现是为了弥补关系数据库的不足，尤其是是在处理超大量的数据时。NoSQL并不是一个数据库的名字，而是一系列不再局限于关系型的数据库的总称。
下面本文将就目前出现的一些NoSQL做一些简要的介绍，以备获悉，并且本文将不断更新，以补充一些新的NoSQL数据库的介绍，并且摒弃那些不再流行的NoSQL数据库，有关NoSQL的最新的数据库信息，可以从网站上面查阅。另外，本文的大多数Linux下面的实验是在ubuntu系统下进行的。
为了更好的了解NoSQL，这里列出了一些NoSQL常用的提升处理能力的非SQL的一些概念，这些概念会一直进行补充。
概念一：键值存储
数据的存储方式是键值对。这样的数据库处理速度一般很快，查询获取数据的方式一般为通过键或者键的正则表达式。
目前本文包含的NoSQL数据库有：memcached，
memcached
该数据库属于把数据存储在内存中的数据库，事实上，当机器断电，内存关闭的时候，memcached也就不复存在，当机器启动，内存重新加载memcached的时候，这已经是一个全新的数据库了，所以需要保存持久的数据一般是不会使用memcached数据库的。由于memcached是全部数据在内存中的，服务器空间，所以具有高速的响应速度，一般被用做高速缓存使用。
memcached数据库是基于键值存储的，并且是临时性的，一些具体的例子如下所示。该例子是使用了Ruby实现。
这个例子实现了在同一个机子中开辟3个memcached，分别对应不同的端口。Ruby访问memcached就像使用Map一样简单。
在ubuntu下面Ruby需要使用memcache-client库来支持，香港服务器，而这个需要使用gem进行安装，香港虚拟主机，所以ubuntu下面的ruby最好采用1.9以上版本。启动一个memcached的应用实例的命令如下：
memcached –d –p 11211(端口) –u nobody(用户名) –c 1024(最大连接数) –m 64(内存空间)
除此之外，repcached工具实现了memcached多个实例之间，数据的相互复制备份。
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