March 2021
Intermediate to advanced
265 pages
6h 50m
Chinese
Content preview from Presto实战
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114
｜
第
7
章
图 7-6：查询计划中的下推
7.7
ETL
和联合查询
提取
、
转换
、
加载
（
extract,
transform, load
，简称
ETL
）是一个术语，指从数据源复制数
据并将其放到另一个数据源的技术。通常在准备目标数据的过程中会有一个从数据源转换
数据的中间步骤。这个过程可能包括丢弃列、进行计算、过滤和清洗数据、
Join
数
据，以
及进行预聚合等，这些都是为了让目标数据更适合查询。
Presto
并不是一个可以与商业解决方案相媲美的
、成熟的
ETL
工具，但它可以通过避
免
ETL
来
提供一些帮助。因为
Presto
可以从数据源查询，所以可能不再需要移动数据。
Presto
可以在数据所在的地方查询数据，以降低管理
ETL
过程的复杂性。
你可能仍需要做某些类型的
ETL
转换
。也许你想查询预聚合的数据，或者你不想给底层系
统带来更多的负载。通过使用
CREATE TABLE AS
或
INSERT SELECT
，你可以将数据从一个数
据源移动到另一个数据源。
在将
Presto
用于
ETL
场景的一大优势是支持关系数据库以外的其他数据源。
7.8
小结
你现在对
Presto
中的连接器有了很好的认识，是时候好好利用它们了。配置好你的
catalog
，准备学习更多关于查询数据源的知识。
这就引出了我们的下一个主题——
SQL
在
Presto
中的使用
。
SQL
知识对于你成功使用
Presto
至关重要，第
8
章和第
9
章会介绍所有你需要了解的内容。
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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.