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LOAD作用是加载文件到表中(Loading files into tables)
下面是官网上为我们列出的语法:
LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)]
LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)] [INPUTFORMAT 'inputformat' SERDE 'serde'] (3.0 or later)
1.加载数据到表中时,Hive不做任何转换。加载操作只是把数据拷贝或移动操作,即移动数据文件到Hive表相应的位置。
2.加载的目标可以是一个表,也可以是一个分区。如果表是分区的,则必须通过指定所有分区列的值来指定一个表的分区。
LOCAL:表示输入文件在本地文件系统(Linux),如果没有加LOCAL,hive则会去HDFS上查找该文件。
OVERWRITE:表示如果表中有数据,则先删除数据,再插入新数据,如果没有这个关键词,则直接附加数据到表中。
PARTITION:如果表中存在分区,可以按照分区进行导入。
# 创建一张员工表
hive> create table emp
> (empno int, ename string, job string, mgr int, hiredate string, salary double, comm double, deptno int)
> ROW FORMAT DELIMITED
> FIELDS TERMINATED BY '\t' ;
OK
Time taken: 0.651 seconds
# 把本地文件系统中emp.txt导入表
hive> LOAD DATA LOCAL INPATH '/home/hadoop/emp.txt' OVERWRITE INTO TABLE emp;
Loading data to table default.emp
Table default.emp stats: [numFiles=1, numRows=0, totalSize=886, rawDataSize=0]
OK
Time taken: 1.848 seconds
# 查看表数据
hive> select * from emp;
OK
7369 SMITH CLERK 7902 1980-12-17 800.0 NULL 20
7499 ALLEN SALESMAN 7698 1981-2-20 1600.0 300.0 30
7521 WARD SALESMAN 7698 1981-2-22 1250.0 500.0 30
7566 JONES MANAGER 7839 1981-4-2 2975.0 NULL 20
7654 MARTIN SALESMAN 7698 1981-9-28 1250.0 1400.0 30
7698 BLAKE MANAGER 7839 1981-5-1 2850.0 NULL 30
7782 CLARK MANAGER 7839 1981-6-9 2450.0 NULL 10
7788 SCOTT ANALYST 7566 1987-4-19 3000.0 NULL 20
7839 KING PRESIDENT NULL 1981-11-17 5000.0 NULL 10
7844 TURNER SALESMAN 7698 1981-9-8 1500.0 0.0 30
7876 ADAMS CLERK 7788 1987-5-23 1100.0 NULL 20
7900 JAMES CLERK 7698 1981-12-3 950.0 NULL 30
7902 FORD ANALYST 7566 1981-12-3 3000.0 NULL 20
7934 MILLER CLERK 7782 1982-1-23 1300.0 NULL 10
# 不用OVERWRITE关键字
hive> LOAD DATA LOCAL INPATH '/home/hadoop/emp.txt' INTO TABLE emp;
# 再次查看
hive> select * from emp;
OK
7369 SMITH CLERK 7902 1980-12-17 800.0 NULL 20
7499 ALLEN SALESMAN 7698 1981-2-20 1600.0 300.0 30
7521 WARD SALESMAN 7698 1981-2-22 1250.0 500.0 30
7566 JONES MANAGER 7839 1981-4-2 2975.0 NULL 20
7654 MARTIN SALESMAN 7698 1981-9-28 1250.0 1400.0 30
7698 BLAKE MANAGER 7839 1981-5-1 2850.0 NULL 30
7782 CLARK MANAGER 7839 1981-6-9 2450.0 NULL 10
7788 SCOTT ANALYST 7566 1987-4-19 3000.0 NULL 20
7839 KING PRESIDENT NULL 1981-11-17 5000.0 NULL 10
7844 TURNER SALESMAN 7698 1981-9-8 1500.0 0.0 30
7876 ADAMS CLERK 7788 1987-5-23 1100.0 NULL 20
7900 JAMES CLERK 7698 1981-12-3 950.0 NULL 30
7902 FORD ANALYST 7566 1981-12-3 3000.0 NULL 20
7934 MILLER CLERK 7782 1982-1-23 1300.0 NULL 10
7369 SMITH CLERK 7902 1980-12-17 800.0 NULL 20
7499 ALLEN SALESMAN 7698 1981-2-20 1600.0 300.0 30
7521 WARD SALESMAN 7698 1981-2-22 1250.0 500.0 30
7566 JONES MANAGER 7839 1981-4-2 2975.0 NULL 20
7654 MARTIN SALESMAN 7698 1981-9-28 1250.0 1400.0 30
7698 BLAKE MANAGER 7839 1981-5-1 2850.0 NULL 30
7782 CLARK MANAGER 7839 1981-6-9 2450.0 NULL 10
7788 SCOTT ANALYST 7566 1987-4-19 3000.0 NULL 20
7839 KING PRESIDENT NULL 1981-11-17 5000.0 NULL 10
7844 TURNER SALESMAN 7698 1981-9-8 1500.0 0.0 30
7876 ADAMS CLERK 7788 1987-5-23 1100.0 NULL 20
7900 JAMES CLERK 7698 1981-12-3 950.0 NULL 30
7902 FORD ANALYST 7566 1981-12-3 3000.0 NULL 20
7934 MILLER CLERK 7782 1982-1-23 1300.0 NULL 10
Time taken: 0.137 seconds, Fetched: 28 row(s)
# 再次OVERWRITE覆盖导入
hive> LOAD DATA LOCAL INPATH '/home/hadoop/emp.txt' OVERWRITE INTO TABLE emp;
# 发现数据被覆盖了
hive> select * from emp;
OK
7369 SMITH CLERK 7902 1980-12-17 800.0 NULL 20
7499 ALLEN SALESMAN 7698 1981-2-20 1600.0 300.0 30
7521 WARD SALESMAN 7698 1981-2-22 1250.0 500.0 30
7566 JONES MANAGER 7839 1981-4-2 2975.0 NULL 20
7654 MARTIN SALESMAN 7698 1981-9-28 1250.0 1400.0 30
7698 BLAKE MANAGER 7839 1981-5-1 2850.0 NULL 30
7782 CLARK MANAGER 7839 1981-6-9 2450.0 NULL 10
7788 SCOTT ANALYST 7566 1987-4-19 3000.0 NULL 20
7839 KING PRESIDENT NULL 1981-11-17 5000.0 NULL 10
7844 TURNER SALESMAN 7698 1981-9-8 1500.0 0.0 30
7876 ADAMS CLERK 7788 1987-5-23 1100.0 NULL 20
7900 JAMES CLERK 7698 1981-12-3 950.0 NULL 30
7902 FORD ANALYST 7566 1981-12-3 3000.0 NULL 20
7934 MILLER CLERK 7782 1982-1-23 1300.0 NULL 10
Time taken: 0.164 seconds, Fetched: 14 row(s)
Standard syntax:
INSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...) [IF NOT EXISTS]] select_statement1 FROM from_statement;
INSERT INTO TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...)] select_statement1 FROM from_statement;
Hive extension (multiple inserts):
FROM from_statement
INSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...) [IF NOT EXISTS]] select_statement1
[INSERT OVERWRITE TABLE tablename2 [PARTITION ... [IF NOT EXISTS]] select_statement2]
[INSERT INTO TABLE tablename2 [PARTITION ...] select_statement2] ...;
FROM from_statement
INSERT INTO TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...)] select_statement1
[INSERT INTO TABLE tablename2 [PARTITION ...] select_statement2]
[INSERT OVERWRITE TABLE tablename2 [PARTITION ... [IF NOT EXISTS]] select_statement2] ...;
Hive extension (dynamic partition inserts):
INSERT OVERWRITE TABLE tablename PARTITION (partcol1[=val1], partcol2[=val2] ...) select_statement FROM from_statement;
INSERT INTO TABLE tablename PARTITION (partcol1[=val1], partcol2[=val2] ...) select_statement FROM from_statement;
官网又给我们列出一大堆语法,看着就很可怕,但是仔细整理后再来看看你会发现并没有什么,下面对其进行分析:
4 使用插入语法会跑mr作业。
5 multiple inserts:代表多行插入。
注:这里有两种插语法,也就是加上OVERWRITE关键字和不加的区别。
# insert overwrite
hive> insert overwrite table emp2 select * from emp;
Query ID = hadoop_20180624141010_3063d504-ff2f-4003-843f-7dca60f1dd7e
Total jobs = 3
Launching Job 1 out of 3
...
OK
Time taken: 19.554 seconds
hive> select * from emp2;
OK
7369 SMITH CLERK 7902 1980-12-17 800.0 NULL 20
7499 ALLEN SALESMAN 7698 1981-2-20 1600.0 300.0 30
7521 WARD SALESMAN 7698 1981-2-22 1250.0 500.0 30
7566 JONES MANAGER 7839 1981-4-2 2975.0 NULL 20
7654 MARTIN SALESMAN 7698 1981-9-28 1250.0 1400.0 30
7698 BLAKE MANAGER 7839 1981-5-1 2850.0 NULL 30
7782 CLARK MANAGER 7839 1981-6-9 2450.0 NULL 10
7788 SCOTT ANALYST 7566 1987-4-19 3000.0 NULL 20
7839 KING PRESIDENT NULL 1981-11-17 5000.0 NULL 10
7844 TURNER SALESMAN 7698 1981-9-8 1500.0 0.0 30
7876 ADAMS CLERK 7788 1987-5-23 1100.0 NULL 20
7900 JAMES CLERK 7698 1981-12-3 950.0 NULL 30
7902 FORD ANALYST 7566 1981-12-3 3000.0 NULL 20
7934 MILLER CLERK 7782 1982-1-23 1300.0 NULL 10
Time taken: 0.143 seconds, Fetched: 14 row(s)
# insert追加
hive> insert into table emp2 select * from emp;
Query ID = hadoop_20180624141010_3063d504-ff2f-4003-843f-7dca60f1dd7e
Total jobs = 3
...
OK
Time taken: 18.539 seconds
hive> select * from emp2;
OK
7369 SMITH CLERK 7902 1980-12-17 800.0 NULL 20
7499 ALLEN SALESMAN 7698 1981-2-20 1600.0 300.0 30
7521 WARD SALESMAN 7698 1981-2-22 1250.0 500.0 30
7566 JONES MANAGER 7839 1981-4-2 2975.0 NULL 20
7654 MARTIN SALESMAN 7698 1981-9-28 1250.0 1400.0 30
7698 BLAKE MANAGER 7839 1981-5-1 2850.0 NULL 30
7782 CLARK MANAGER 7839 1981-6-9 2450.0 NULL 10
7788 SCOTT ANALYST 7566 1987-4-19 3000.0 NULL 20
7839 KING PRESIDENT NULL 1981-11-17 5000.0 NULL 10
7844 TURNER SALESMAN 7698 1981-9-8 1500.0 0.0 30
7876 ADAMS CLERK 7788 1987-5-23 1100.0 NULL 20
7900 JAMES CLERK 7698 1981-12-3 950.0 NULL 30
7902 FORD ANALYST 7566 1981-12-3 3000.0 NULL 20
7934 MILLER CLERK 7782 1982-1-23 1300.0 NULL 10
7369 SMITH CLERK 7902 1980-12-17 800.0 NULL 20
7499 ALLEN SALESMAN 7698 1981-2-20 1600.0 300.0 30
7521 WARD SALESMAN 7698 1981-2-22 1250.0 500.0 30
7566 JONES MANAGER 7839 1981-4-2 2975.0 NULL 20
7654 MARTIN SALESMAN 7698 1981-9-28 1250.0 1400.0 30
7698 BLAKE MANAGER 7839 1981-5-1 2850.0 NULL 30
7782 CLARK MANAGER 7839 1981-6-9 2450.0 NULL 10
7788 SCOTT ANALYST 7566 1987-4-19 3000.0 NULL 20
7839 KING PRESIDENT NULL 1981-11-17 5000.0 NULL 10
7844 TURNER SALESMAN 7698 1981-9-8 1500.0 0.0 30
7876 ADAMS CLERK 7788 1987-5-23 1100.0 NULL 20
7900 JAMES CLERK 7698 1981-12-3 950.0 NULL 30
7902 FORD ANALYST 7566 1981-12-3 3000.0 NULL 20
7934 MILLER CLERK 7782 1982-1-23 1300.0 NULL 10
Time taken: 0.132 seconds, Fetched: 28 row(s)
INSERT INTO TABLE tablename [PARTITION (partcol1[=val1], partcol2[=val2] ...)] VALUES values_row [, values_row ...]
hive> create table stu(
> id int,
> name string
> )
> ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t';
OK
Time taken: 0.253 seconds
hive> insert into table stu values (1,"zhangsan");
Query ID = hadoop_20180624141010_3063d504-ff2f-4003-843f-7dca60f1dd7e
Total jobs = 3
...
OK
Time taken: 16.589 seconds
hive> select * from stu;
OK
1 zhangsan
Time taken: 0.123 seconds, Fetched: 1 row(s)
查询结果可以通过语句插入文件系统中:
Standard syntax:(标准语法)
INSERT OVERWRITE [LOCAL] DIRECTORY directory1
[ROW FORMAT row_format] [STORED AS file_format] (Note: Only available starting with Hive 0.11.0)
SELECT ... FROM ...
Hive extension (multiple inserts):(导出多条记录)
FROM from_statement
INSERT OVERWRITE [LOCAL] DIRECTORY directory1 select_statement1
[INSERT OVERWRITE [LOCAL] DIRECTORY directory2 select_statement2] ...
row_format
: DELIMITED [FIELDS TERMINATED BY char [ESCAPED BY char]] [COLLECTION ITEMS TERMINATED BY char]
[MAP KEYS TERMINATED BY char] [LINES TERMINATED BY char]
[NULL DEFINED AS char] (Note: Only available starting with Hive 0.13)
**LOCAL**:加上LOCAL关键字代表导入本地系统,不加默认导入HDFS;
**STORED AS**:可以指定存储格式。
```shell
hive> insert overwrite local directory '/home/hadoop/stu' ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t' select * from stu;
Query ID = hadoop_20180624153131_97271014-abcf-4e70-b318-7de85d27c97f
Total jobs = 1
...
OK
Time taken: 15.09 seconds
# 结果
[hadoop@hadoop000 stu]$ pwd
/home/hadoop/stu
[hadoop@hadoop000 stu]$ cat 000000_0
1 zhangsan
# 导出多条记录
hive> from emp
> INSERT OVERWRITE LOCAL DIRECTORY '/home/hadoop/tmp/hivetmp1'
> ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
> select empno, ename
> INSERT OVERWRITE LOCAL DIRECTORY '/home/hadoop/tmp/hivetmp2'
> ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
> select ename;
Query ID = hadoop_20180624153131_97271014-abcf-4e70-b318-7de85d27c97f
Total jobs = 1
...
OK
Time taken: 16.261 seconds
# 结果
[hadoop@hadoop000 tmp]$ cd hivetmp1
[hadoop@hadoop000 hivetmp1]$ ll
total 4
-rw-r--r-- 1 hadoop hadoop 154 Jun 24 15:39 000000_0
[hadoop@hadoop000 hivetmp1]$ cat 000000_0
7369 SMITH
7499 ALLEN
7521 WARD
7566 JONES
7654 MARTIN
7698 BLAKE
7782 CLARK
7788 SCOTT
7839 KING
7844 TURNER
7876 ADAMS
7900 JAMES
7902 FORD
7934 MILLER
[hadoop@hadoop000 hivetmp1]$ cd ..
[hadoop@hadoop000 tmp]$ cd hivetmp2
[hadoop@hadoop000 hivetmp2]$ cat 000000_0
SMITH
ALLEN
WARD
JONES
MARTIN
BLAKE
CLARK
SCOTT
KING
TURNER
ADAMS
JAMES
FORD
MILLER
参考: https://blog.csdn.net/yu0_zhang0/article/details/79007784
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