March 2021
Intermediate to advanced
265 pages
6h 50m
Chinese
Content preview from Presto实战
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
156
｜
第
9
章
下面是该函数的一个实例——解析
URL
参数：
SELECT split_to_map('userid=1234&reftype=email&device=mobile', '&', '=');
_col0
---------------------------------------------
{device=mobile, userid=1234, reftype=email}
(1 row)
当同一个键出现多次时，
split_to_map
函数会返回错误。
类似的函数
split_to_multimap
可以在一个键重复出现时使用。假定前面的例子中有一个
重复的
device
项：
SELECT
split_to_multimap(
'userid=1234&reftype=email&device=mobile&device=desktop',
'&',
'=');
------------------------------------------------------------
{device=[mobile, desktop], userid=[1234], reftype=[email]}
(1 row)
9.12
Unicode
如表
9-8
所示，
Presto
提供了一组
Unicode
函数
。这些函数可以在
UTF-8
有效编码的
Unicode
码点上工作。这些函数区别对待每个码点，即使多个码点表示单个字符时也是如此。
表9-8：与Unicode编码相关的函数
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.