March 2021
Intermediate to advanced
265 pages
6h 50m
Chinese
Content preview from Presto实战
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42
｜
第
4
章
如果无法接收到一个工作节点的心跳信号，节点发现服务就会触发错误检测器，此后该工
作节点不会再参与新的任务。
为了简化部署并避免运行额外的服务，
Presto
的协调器通常会运行一个内嵌版的节点发现
服务。因为它与
Presto
共享一个
HTTP
服务端，所以使用同一个端口。
因此，工作节点通常将节点发现服务的配置指向协调器的主机名和端口。
4.4
工作节点
工作节点
是
Presto
集群中的一个服务端程序
。它负责执行协调器分配的任务并处理数据。
工作节点使用连接器从数据源获取数据，它们相互之间也会交换中间数据。它们将最终的
结果数据发送给协调器，由协调器负责收集来自各个工作节点的结果并发送给客户端。
在安装时，工作节点需要知道集群的节点发现服务所在的主机名或
IP
地址。工作节点会在
启动时将自己注册到节点发现服务上，以便协调器向其分配任务。
工作节点使用
HTTP
与其他工作节点和协调器通信。
图
4-4
展示了多个工作节点如何从数据源获取数据并合作处理数据
，直到其中一个节点可
以向协调器发送结果。
工作节点
工作节点
工作节点工作节点
图 4-4：集群中的工作节点相互协作来处理 SQL 语句和数据
4.5
基于连接器的架构
Presto
存储与计算分离的核心是基于连接器的架构。
连接器
为
Presto
提供了连接任意数据
源的接口。
每个连接器在底层数据源上提供了一个基于表的抽象。只要数据可以用
Presto
支持
的数据
类型表示成表、列和行，就可以创建连接器并让查询引擎使用这些数据进行查询处理。
Presto
提供了
服务提供者接口
（
service ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.