本文具体探讨 MySQL 数据实时同步到 Elasticsearch (以下简称 ES ) 技术方案和思考，同时使用一定篇幅介绍一些前置知识，从理论到实践，让读者更好的理解这块内容和相关问题。包括：
为什么我们要将数据从 MySQL 实时同步到 ES ，本质是什么？
为什么是 ES，而不是其他 OLAP 引擎？
MySQL 到 ES 数据实时同步方案中有哪些细节需要注意？
MySQL 到 ES 数据实时同步方案可以有哪些选择，优缺点是什么？
相信看完本文，你会对 MySQL 数据实时同步到 ES 有更多的了解。
Database normalization is the process of structuring a database, usually a relational database, in accordance with a series of so-called normal forms in order to reduce data redundancy and improve data integrity. It was first proposed by Edgar F. Codd as part of his relational model.
Denormalization is a strategy used on a previously-normalized database to increase performance. In computing, denormalization is the process of trying to improve the read performance of a database, at the expense of losing some write performance, by adding redundant copies of data or by grouping data. It is often motivated by performance or scalability in relationaldatabase software needing to carry out very large numbers of read operations. Denormalization differs from the unnormalized form in that denormalization benefits can only be fully realized on a data model that is otherwise normalized.