March 2021
Intermediate to advanced
265 pages
6h 50m
Chinese
Content preview from Presto实战
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高级
SQL
特性
｜
161
SELECT user, permission
FROM permissions,
UNNEST(permissions.roles) AS t1(roles),
UNNEST(t1.roles) AS t2(permission)
WHERE permission = 'Audit_Read';
user | permission
--------+-----------
martin | Audit_Read
(1 row)
9.15
JSON
函数
在现代应用程序和系统中，
JSON
格式的数据无处不在，应用范围极广。
JavaScript Object
Notation
（
JSON
）是一种可读性佳且很灵活的数据格式，常用于
We
b
应用程序，作为浏
览器和服务器之间的数据传输格式。很多需要分析的数据来自于
We
b
流量，因此经常使用
JSON
格式输出和保存。专用的文档存储以及许多关系数据库系统现在支持
JSON
数据。
Presto
是一个
SQL-on-Anything
的引擎
，它能以
JSON
格式从数据源中检索数据。例如，
Kafka
、
Elasticsearch
和
MongoDB
连接器都返回
JSON
格式的数据
，或者可以暴露源
JSON
数据。
Presto
也可以使用
HDFS
或云对象存储中的
JSON
文
件。
Presto
并不强制连接器将
JSON
格
式的数据转换为带有列和行的严格的关系数据结构，相反，可以用表
9-12
中的函
数对
JSON
数据进行操作，这使得用户可以对原始数据执行他们想要的操作。 ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.