hive学习笔记之-数据类型
数据类型
Hive基本的数据类型：
Hive集合数据类型：
另外还有一个复合数据类型，可以综合上面的数据类型组合到一起。
· union: UNIONTYPE
类型说明
时间戳
支持传统的unix时间戳,可选的纳秒级精度。
支持的转换:
l 整型数值类型：解读为以秒为单位的UNIX时间戳
l 浮动点数值类型：解读为以秒和小数精度为单位的UNIX时间戳。
l 字符串：JDBC兼容的java.sql.Timestamp格式“YYYY-MM-DD HH：MM：SS.fffffffff”（9位小数位精度）
时间戳被解释是与timezone无关，存储为从UNIX纪元的偏移量。提供便利的UDF和时区转换（to_utc_timestamp，from_utc_timestamp）。
所有现有datetime的UDF（月，日，年，小时，等）可以工作于TIMESTAMP数据类型。
限定符
Hive默认的限定符：
下面两个建表语句是一样的。
隐式的限定符语句：
CREATE TABLEemployees (
name STRING,
salary FLOAT,
subordinatesARRAY
deductions MAP
address STRUCT
显式的限定符语句：
CREATE TABLEemployees (
name STRING,
salary FLOAT,
subordinatesARRAY
deductions MAP
address STRUCT
)
ROW FORMATDELIMITED
FIELDSTERMINATED BY '\001'
COLLECTION ITEMSTERMINATED BY '\002'
MAP KEYSTERMINATED BY '\003'
LINES TERMINATEDBY '\n'
STORED ASTEXTFILE;
要导入的文件格式
John Doe^A100000.0^AMary Smith^BTodd Jones^AFederal Taxes^C.2^BStateTaxes^C.05^BInsurance^C.1^A1 Michigan Ave.^BChicago^BIL^B60600
Mary Smith^A80000.0^ABill King^AFederal Taxes^C.2^BState Taxes^C.05^BInsurance^C.1^A100 Ontario St.^BChicago^BIL^B60601
Todd Jones^A70000.0^AFederalTaxes^C.15^BState Taxes^C.03^BInsurance^C.1^A200 Chicago Ave.^BOak Park^BIL^B60700
Bill King^A60000.0^AFederal Taxes^C.15^BState Taxes^C.03^BInsurance^C.1^A300 Obscure Dr.^BObscuria^BIL^B60100
下面是导入首行记录的格式样本结构：
{
"name": "John Doe",
"salary": 100000.0,
"subordinates": ["MarySmith", "Todd Jones"],
"deductions": {
"Federal Taxes": .2,
"State Taxes": .05,
"Insurance": .1
},
"address":{
"street": "1 Michigan Ave.",
"city": "Chicago",
"state": "IL",
"zip": 60600
}
}
当然我们可以自己可以自定列值的限定符，如下：
CREATE TABLEemployees (
name STRING,
salary FLOAT,
subordinates ARRAY
deductions MAP
address STRUCT
)
ROW FORMATDELIMITED
FIELDSTERMINATED BY ','
COLLECTION ITEMSTERMINATED BY '|'
MAP KEYSTERMINATED BY ':';
注意：
1. 由于field, collection, and key-value的分隔默认就是TEXTFILE格式，所以上面可以省略掉STORED AS TEXTFILE子句。
2. 由于目前hive支持的行分隔符只有/n（换行符），所以LINES TERMINATED BY '\n'子句也可以去掉。
3. 关于怎么制作Hive默认分隔符的数据文件见：http://www.myexception.cn/software-architecture-design/1351552.html
按表的定义文件的格式：
John Doe,100000.0,MarySmith|Todd Jones,Federal Taxes:.2|State Taxes:.05|Insurance:.1,1 MichiganAve.|Chicago|IL|60600
MarySmith,80000.0,Bill King,Federal Taxes:.2|State Taxes:.05|Insurance:.1,100Ontario St.|Chicago|IL|60601
ToddJones,70000.0,,Federal Taxes:.15|State Taxes:.03|Insurance:.1,200 ChicagoAve.|Oak Park|IL|60700
BillKing,60000.0,,Federal Taxes:.15|State Taxes:.03|Insurance:.1,300 ObscureDr.|Obscuria|IL|60100
导入数据：
load data localinpath '/app/hadoop/data/employees2' overwrite into table employees;
查看数据：
hive(default)> select * from employees2;
OK
John Doe 100000.0 ["Mary Smith","ToddJones"] {"FederalTaxes":0.2,"State Taxes":0.05,"Insurance":0.1} {"street":"1 Michigan Ave.","city":"Chicago","state":"IL","zip":60600}
Mary Smith 80000.0 ["Bill King"] {"Federal Taxes":0.2,"StateTaxes":0.05,"Insurance":0.1} {"street":"100 Ontario St.","city":"Chicago","state":"IL","zip":60601}
Todd Jones 70000.0 [] {"FederalTaxes":0.15,"State Taxes":0.03,"Insurance":0.1} {"street":"200 Chicago Ave.","city":"Oak Park","state":"IL","zip":60700}
Bill King 60000.0 [] {"FederalTaxes":0.15,"State Taxes":0.03,"Insurance":0.1} {"street":"300 Obscure Dr.","city":"Obscuria","state":"IL","zip":60100}
Time taken:0.085 seconds, Fetched: 4 row(s)
参考：
1.Hive编程指南
2.https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Types