January 2018
Beginner to intermediate
234 pages
7h 8m
Chinese
Content preview from Kafka权威指南
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初识
Kafka
｜
5
1.2.3
主题和分区
Kafka
的消息通过
主题
进行分类。主题就好比数据库的表，或者文件系统里的文件夹。主
题可以被分为若干个
分区
，一个分区就是一个提交日志。消息以追加的方式写入分区，然
后以先入先出的顺序读取。要注意，由于一个主题一般包含几个分区，因此无法在整个主
题范围内保证消息的顺序，但可以保证消息在单个分区内的顺序。图
1-5
所示的主题有
4
个分区，消息被追加写入每个分区的尾部。
Kafka
通过分区来实现数据冗余和伸缩性。分
区可以分布在不同的服务器上，也就是说，一个主题可以横跨多个服务器，以此来提供比
单个服务器更强大的性能。
主题“topicName”
分区0
分区1
分区2
分区3
消息写入
图 1-5：包含多个分区的主题表示
我们通常会使用
流
这个词来描述
Kafka
这类系统的数据。很多时候，人们把一个主题的数
据看成一个流，不管它有多少个分区。流是一组从生产者移动到消费者的数据。当我们讨
论流式处理时，一般都是这样描述消息的。
Kafka Streams
、
Apache Samza
和
Storm
这些框
架以实时的方式处理消息，也就是所谓的流式处理。我们可以将流式处理与离线处理进行
比较，比如
Hadoop
就是被设计用于在稍后某个时刻处理大量的数据。第
11
章将会介绍流
式处理。
1.2.4
生产者和消费者
Kafka
的客户端就是
Kafka
系统的用户，它们被分为两种基本类型：生产者和消费者。除
此之外，还有其他高级客户端
API
——用于数据集成的
Kafka Connect API
和用于流式处理
的
Kafka ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.