Hive Serde
目的：
Hive Serde用来做序列化和反序列化，构建在数据存储和执行引擎之间，对两者实现解耦。
应用场景：
1、hive主要用来存储结构化数据，如果结构化数据存储的格式嵌套比较复杂的时候，可以使用serde的方式，利用正则表达式匹配的方法来读取数据，例如，表字段如下：id,name,map<string,array<map<string,string>>>
2、当读取数据的时候，数据的某些特殊格式不希望显示在数据中，如：
192.168.57.4 - - [29/Feb/2019:18:14:35 +0800] "GET /bg-upper.png HTTP/1.1" 304 -
不希望数据显示的时候包含[]或者"",此时可以考虑使用serde的方式
语法规则：
row_format
: DELIMITED
[FIELDS TERMINATED BY char [ESCAPED BY char]]
[COLLECTION ITEMS TERMINATED BY char]
[MAP KEYS TERMINATED BY char]
[LINES TERMINATED BY char]
: SERDE serde_name [WITH SERDEPROPERTIES (property_name=property_value, property_name=property_value, ...)]
应用案例：
1、数据文件
192.168.57.4 - - [29/Feb/2019:18:14:35 +0800] "GET /bg-upper.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:35 +0800] "GET /bg-nav.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:35 +0800] "GET /asf-logo.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:35 +0800] "GET /bg-button.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:35 +0800] "GET /bg-middle.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET / HTTP/1.1" 200 11217
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET / HTTP/1.1" 200 11217
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /tomcat.css HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /tomcat.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /asf-logo.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /bg-middle.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /bg-button.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /bg-nav.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /bg-upper.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET / HTTP/1.1" 200 11217
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /tomcat.css HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /tomcat.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET / HTTP/1.1" 200 11217
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /tomcat.css HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /tomcat.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /bg-button.png HTTP/1.1" 304 -
192.168.57.4 - - [29/Feb/2019:18:14:36 +0800] "GET /bg-upper.png HTTP/1.1" 304 -
2、基本操作：
--创建表
CREATE TABLE logtbl (
host STRING,
identity STRING,
t_user STRING,
time STRING,
request STRING,
referer STRING,
agent STRING)
ROW FORMAT SERDE 'org.apache.hadoop.hive.serde2.RegexSerDe'
WITH SERDEPROPERTIES (
"input.regex" = "([^ ]*) ([^ ]*) ([^ ]*) \[(.*)\] "(.*)" (-|[0-9]*) (-|[0- 9]*)"
)
STORED AS TEXTFILE;
--加载数据
load data local inpath '/root/data/log' into table logtbl;
--查询操作
select * from logtbl;
--数据显示如下（不包含[]和"）
192.168.57.4 - - 29/Feb/2019:18:14:35 +0800 GET /bg-upper.png HTTP/1.1 304 -
192.168.57.4 - - 29/Feb/2019:18:14:35 +0800 GET /bg-nav.png HTTP/1.1 304 -
192.168.57.4 - - 29/Feb/2019:18:14:35 +0800 GET /asf-logo.png HTTP/1.1 304 -
192.168.57.4 - - 29/Feb/2019:18:14:35 +0800 GET /bg-button.png HTTP/1.1 304 -
192.168.57.4 - - 29/Feb/2019:18:14:35 +0800 GET /bg-middle.png HTTP/1.1 304 -