March 2021
Intermediate to advanced
265 pages
6h 50m
Chinese
Content preview from Presto实战
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120
｜
第
8
章
8.3
catalog
如第
6
章中所述，
Presto catalog
代表在
catalog
属性文件中使用连接器配置的数据源。
catalog
包含一个或多个
schema
，而
schema
提供了表的集合。
例如，你可以配置一个
PostgreSQL
catalog
来访问
PostgreSQL
上的关系数据库；也可以配
置一个
JMX
catalog
，通过
JMX
连接器对
JMX
信息进行访问；还可以通过使用
Hive
连接
器的
catalog
连接到
HDFS
对象存储数据源
。当在
Presto
中运行一个
SQL
语句时，你是在
一个或多个
catalog
上运行它。
多个
cat
alog
可以使用同一个连接器。例如，你可以创建两个独立的
catalog
来暴露两个运
行在同一服务器上的
PostgreSQL
数据库。
在
Presto
中寻找一个表时
，完全限定表名总是以
catalog
为根。例如，完全限定表名
hive.
test_data.test
指的是
hive
catalog
、
test_data
schema
中的
test
表。
可以通过访问系统数据来查看
Presto
服务器中的可用
catalog
列表：
SHOW CATALOGS;
Catalog
---------
blackhole
hive
jmx
postgresql
kafka
system
(6 rows)
catalog
、
schema
和表信息不由
Presto
存储，
Presto
也没有自己的
catalog
。连接器负责向
Presto
提供这些信息
。通常情况下，这是通过从底层数据库查询 ...
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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.