MongoDB的利弊？ [英] Pros and cons of MongoDB?

问题描述

有人能告诉我什么是mongodb的利弊，特别是与关系数据库？包括ACID，可扩展性，吞吐量，主内存使用，插入/查询性能和索引大小等。

Could anybody tell me what is the pros and cons of mongodb, especially comparing with the relational database? including ACID, scalability, throughput, main memory usage, insert/query performance and index size etc.

推荐答案

MongoDB

优点：

• 无架构。如果你有一个灵活的模式，这是一个文档存储如
  MongoDB的理想选择。这难以在RDBMS


• 轻松扩展中以高性能的方式实现。使用副本集缩放读取。使用分片（自动平衡）缩放写入。只是启动另一台机器，离开你去。添加更多计算机=添加更多RAM以分配工作集。


• 费用。取决于当前哪个RDBMS，但是MongoDB是免费的，并且可以在Linux上运行，非常适合在更便宜的商品套件上运行。


• 您可以根据需要选择什么级别的一致性数据（例如，更快的性能=火灾和忘记插入到MongoDB，性能更慢=等待插入已经被复制到多个节点，然后返回）

• schema-less. If you have a flexible schema, this is ideal for a document store like MongoDB. This is difficult to implement in a performant manner in RDBMS
• ease of scale-out. Scale reads by using replica sets. Scale writes by using sharding (auto balancing). Just fire up another machine and away you go. Adding more machines = adding more RAM over which to distribute your working set.
• cost. Depends on which RDBMS of course, but MongoDB is free and can run on Linux, ideal for running on cheaper commodity kit.
• you can choose what level of consistency you want depending on the value of the data (e.g. faster performance = fire and forget inserts to MongoDB, slower performance = wait til insert has been replicated to multiple nodes before returning)

缺点：

• MongoDB中的数据大小通常较高，


• 不支持事务 - 支持某些原子操作，在单个文档级别


• 在当前Map / Reduce（例如进行聚合/数据分析）是可以的，但不是很快的。因此，如果需要，可能需要将类似Hadoop的内容添加到混合


• 减少最新信息/快速发展的产品

• Data size in MongoDB is typically higher due to e.g. each document has field names stored it
• less flexibity with querying (e.g. no JOINs)
• no support for transactions - certain atomic operations are supported, at a single document level
• at the moment Map/Reduce (e.g. to do aggregations/data analysis) is OK, but not blisteringly fast. So if that's required, something like Hadoop may need to be added into the mix
• less up to date information available/fast evolving product

我最近在MongoDB上记录了我的想法，因为有人来自SQL Server后台，因此您可能对此感兴趣（上面只是一些要点）。

I recently blogged my thoughts on MongoDB as someone coming from SQL Server background, so you might be interested in that (above are just some of the main points).

如果你正在寻找一个MongoDB比RDBMS更好的答案 - 那么IMHO有没有答案。 NoSQL技术（如MongoDB）提供了一种替代方案，它补充了RDBMS技术。一个人可能更适合于某个特定的目的，而不是另一个，所以它是所有关于什么是最适合你的一个给定的要求。

If you're looking for a "Is MongoDB better than RDBMS" answer - then IMHO there is no answer. NoSQL technologies like MongoDB provide an alternative, that complements RDBMS technologies. One may be better suited to a particular purpose than the other, so it's all about making a call on what is best for you for a given requirement.

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