说明：  mongodb是一个高性能的非关系型数据库，其底层还实现了一个分布式文件系统，可用于各种云计算。基于mongodb做搜索引擎也是非常好的选择，用它给数以亿计的网页建立反向索引也是轻而易举的事情！！！本书由维护mongodb的核心人员所写，详细且清晰的介绍了mongodb。
(mongodb is a high performance non-relational database, the bottom also implements a distributed file system, can be used for a variety of cloud computing. Search engine is based on mongodb do a very good choice, use it to create reverse index billions of web pages is a breeze! ! ! Written by the core staff to maintain mongodb written, detailed and clear presentation of the mongodb.)