From 508fa4bd99d31fdffe6992ad6824b9e2d98047c0 Mon Sep 17 00:00:00 2001 From: luotitan Date: Sun, 4 Dec 2016 21:28:11 +0800 Subject: [PATCH] chapter41_part1: /400_Relationships/10_Intro.asciidoc (#348) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * 重新提交 * 根据node review意见修改 --- 400_Relationships/10_Intro.asciidoc | 64 +++++++++++------------------ 1 file changed, 23 insertions(+), 41 deletions(-) diff --git a/400_Relationships/10_Intro.asciidoc b/400_Relationships/10_Intro.asciidoc index 438c2d8ac..6980919fd 100644 --- a/400_Relationships/10_Intro.asciidoc +++ b/400_Relationships/10_Intro.asciidoc @@ -1,61 +1,43 @@ [[relations]] -== Handling Relationships +== 关联关系处理 -In the real world, relationships((("relationships"))) matter: blog posts have comments, bank -accounts have transactions, customers have bank accounts, orders have order -lines, and directories have files and subdirectories. +现实世界有很多重要的关联关系((("relationships")))：博客帖子有一些评论，银行账户有多次交易记录，客户有多个银行账户，订单有多个订单明细，文件目录有多个文件和子目录。 -Relational databases are specifically designed--and this will not come as a -surprise to you--to manage((("relational databases", "managing relationships"))) relationships: +关系型数据库被明确设计--毫不意外--用来进行关联关系管理((("relational databases", "managing relationships")))： -* Each entity (or _row_, in the relational world) can be uniquely identified - by a _primary key_.((("primary key"))) +* 每个实体（或 _行_ ，在关系世界中）可以被 _主键_ 唯一标识。((("primary key"))) -* Entities are _normalized_. The data for a unique entity is stored only - once, and related entities store just its primary key. Changing the data of - an entity has to happen in only one place.((("joins", "in relational databases"))) +* 实体 _规范化_ （范式）。唯一实体的数据只存储一次，而相关实体只存储它的主键。只能在一个具体位置修改这个实体的数据。((("joins", "in relational databases"))) -* Entities can be joined at query time, allowing for cross-entity search. +* 实体可以进行关联查询，可以跨实体搜索。 -* Changes to a single entity are _atomic_, _consistent_, _isolated_, and - _durable_. (See http://en.wikipedia.org/wiki/ACID_transactions[_ACID Transactions_] - for more on this subject.) +* 单个实体的变化是 _原子的_ ， _一致的_ ， _隔离的_ ， 和 + _持久的_ 。 （可以在 http://en.wikipedia.org/wiki/ACID_transactions[_ACID Transactions_] + 中查看更多细节。） -* Most relational databases support ACID transactions across multiple - entities. +* 大多数关系数据库支持跨多个实体的 ACID 事务。 -But relational ((("ACID transactions")))databases do have their limitations, besides their poor support -for full-text search. Joining entities at query time is expensive--the more -joins that are required, the more expensive the query. Performing joins -between entities that live on different hardware is so expensive that it is -just not practical. This places a limit on the amount of data that can be -stored on a single server. +但是关系型数据库((("ACID transactions")))有其局限性，包括对全文检索有限的支持能力。 +实体关联查询时间消耗是很昂贵的，关联的越多，消耗就越昂贵。特别是跨服务器进行实体关联时成本极其昂贵，基本不可用。 +但单个的服务器上又存在数据量的限制。 -Elasticsearch, like((("NoSQL databases"))) most NoSQL databases, treats the world as though it were -flat. An index is a flat collection of independent documents.((("indices"))) A single -document should contain all of the information that is required to decide -whether it matches a search request. +Elasticsearch ，和大多数 NoSQL 数据库类似，是扁平化的。索引是独立文档的集合体。 +((("indices"))) 文档是否匹配搜索请求取决于它是否包含所有的所需信息。 -While changing the data of a single document in Elasticsearch is -http://en.wikipedia.org/wiki/ACID_transactions[ACIDic], transactions -involving multiple documents are not. There is no way to roll back the index -to its previous state if part of a transaction fails. +Elasticsearch 中单个文档的数据变更是 http://en.wikipedia.org/wiki/ACID_transactions[ACIDic] 的， +而涉及多个文档的事务则不是。当一个事务部分失败时，无法回滚索引数据到前一个状态。 -This FlatWorld has its advantages: +扁平化有以下优势： -* Indexing is fast and lock-free. -* Searching is fast and lock-free. -* Massive amounts of data can be spread across multiple nodes, because each - document is independent of the others. +* 索引过程是快速和无锁的。 +* 搜索过程是快速和无锁的。 +* 因为每个文档相互都是独立的，大规模数据可以在多个节点上进行分布。 -But relationships matter. Somehow, we need to bridge the gap between -FlatWorld and the real world.((("relationships", "techniques for managing relational data in Elasticsearch"))) Four common techniques are used to manage -relational data in Elasticsearch: +但关联关系仍然非常重要。某些时候，我们需要缩小扁平化和现实世界关系模型的差异。((("relationships", "techniques for managing relational data in Elasticsearch")))以下四种常用的方法，用来在 Elasticsearch 中进行关系型数据的管理： * <> * <> * <> * <> -Often the final solution will require a mixture of a few of these techniques. - +通常都需要结合其中的某几个方法来得到最终的解决方案。