什么是“面向文档” vs. Key-Value在谈论MongoDB和Cassandra时的平均值？ [英] What does "Document-oriented" vs. Key-Value mean when talking about MongoDB vs Cassandra?
问题描述
使用基于文档的NoSQL选项如何处理KV商店，反之亦然？
What does going with a document based NoSQL option buy you over a KV store, and vice-versa?
推荐答案
键值存储提供了最简单的可能的数据模型，并且正是名称所暗示的：它是一个存储系统，存储由键索引的值。您限制为按键查询，并且值为不透明，商店不知道有关这些商品的任何 。这允许非常快速的读写操作（一个简单的磁盘访问），我认为这个模型是一种非易失性缓存（即，如果你需要快速访问长期数据的密钥）。
A key-value store provides the simplest possible data model and is exactly what the name suggests: it's a storage system that stores values indexed by a key. You're limited to query by key and the values are opaque, the store doesn't know anything about them. This allows very fast read and write operations (a simple disk access) and I see this model as a kind of non volatile cache (i.e. well suited if you need fast accesses by key to long-lived data).
以文档为导向的数据库扩展了以前的模型，并且值以结构化格式（文档，因此名称）数据库可以理解。例如，文档可以是博客帖子和评论和以非规范化方式存储的代码。由于数据透明，商店可以做更多的工作（如文档的索引字段），并且不限于按键查询。正如我暗示的，这样的数据库允许通过单个查询获取整个页面的数据，非常适合面向内容的应用程序（这就是为什么像Facebook或亚马逊这样的大型网站喜欢它们）。
A document-oriented database extends the previous model and values are stored in a structured format (a document, hence the name) that the database can understand. For example, a document could be a blog post and the comments and the tags stored in a denormalized way. Since the data are transparent, the store can do more work (like indexing fields of the document) and you're not limited to query by key. As I hinted, such databases allows to fetch an entire page's data with a single query and are well suited for content oriented applications (which is why big sites like Facebook or Amazon like them).
其他种类的NoSQL数据库包括面向列的存储器，图形数据库甚至对象数据库。
Other kinds of NoSQL databases include column-oriented stores, graph databases and even object databases. But this goes beyond the question.
- Comparing Document Databases to Key-Value Stores
- Analysis of the NoSQL Landscape
- Thinking about NoSQL databases (classification and use cases)
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