Hive基本操作
数据库操作
查看所有的数据库
hive> show databases ;
使用数据库default
hive> use default;
查看数据库信息
hive > describe database default;
OK
db_name comment location owner_name owner_type parameters
default Default Hive database hdfs://hadoop1:8020/user/hive/warehouse public ROLE
Time taken: 0.042 seconds, Fetched: 1 row(s)
显示地展示当前使用的数据库
hive> set hive.cli.print.current.db=true;
hive(default)>
Hive显示列头
hive (default)> set hive.cli.print.header=true;
hive (default)> desc addressall_2015_07_09;
OK
col_name data_type comment
_c0 string
addr1 bigint
addr2 bigint
addr3 bigint
Time taken: 0.182 seconds, Fetched: 4 row(s)
hive (default)> select * from addressall_2015_07_09;
OK
addressall_2015_07_09._c0 addressall_2015_07_09.addr1 addressall_2015_07_09.addr2 addressall_2015_07_09.addr3
2015_07_09 536 488 493
Time taken: 10.641 seconds, Fetched: 1 row(s)
创建数据库命令
hive (default)> create database liguodong;
OK
Time taken: 10.128 seconds
切换当前的数据库
hive (default)> use liguodong;
OK
Time taken: 0.031 seconds
hive (liguodong)>
删除数据库
删除数据库的时候，不允许删除有数据的数据库，如果数据库里面有数据则会报错。如果要忽略这些内容，则在后面增加CASCADE关键字，则忽略报错，删除数据库。
hive> DROP DATABASE DbName CASCADE(可选);
hive> DROP DATABASE IF EXISTS DbName CASCADE;
表操作
查看当前DB有啥表
hive> SHOW TABLES IN DbName;
hive (liguodong)> SHOW TABLES IN liguodong;
OK
tab_name
Time taken: 0.165 seconds
也可以使用正则表达式 hive> SHOW TABLES LIKE 'h*';
hive (default)> SHOW TABLES LIKE '*all*' ;
OK
tab_name
addressall_2015_07_09
Time taken: 0.039 seconds, Fetched: 1 row(s)
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获得表的建表语句
hive (default)> show create table address1_2015_07_09;
OK
createtab_stmt
CREATE TABLE `address1_2015_07_09`(
`addr1` bigint)
ROW FORMAT SERDE
'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe'
STORED AS INPUTFORMAT
'org.apache.hadoop.mapred.TextInputFormat'
OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
LOCATION
'hdfs://nameservice1/user/hive/warehouse/address1_2015_07_09'
TBLPROPERTIES (
'COLUMN_STATS_ACCURATE'='true',
'numFiles'='1',
'numRows'='0',
'rawDataSize'='0',
'totalSize'='4',
'transient_lastDdlTime'='1436408451')
Time taken: 0.11 seconds, Fetched: 17 row(s)
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创建表
CREATE [TEMPORARY] [EXTERNAL] TABLE [IF NOT EXISTS] [db_name.]table_name -- (Note: TEMPORARY available in Hive 0.14.0 and later)
[(col_name data_type [COMMENT col_comment], ...)]
[COMMENT table_comment]
[PARTITIONED BY (col_name data_type [COMMENT col_comment], ...)]
[CLUSTERED BY (col_name, col_name, ...) [SORTED BY (col_name [ASC|DESC], ...)] INTO num_buckets BUCKETS]
[SKEWED BY (col_name, col_name, ...) -- (Note: Available in Hive 0.10.0 and later)]
ON ((col_value, col_value, ...), (col_value, col_value, ...), ...)
[STORED AS DIRECTORIES]
[
[ROW FORMAT row_format]
[STORED AS file_format]
| STORED BY 'storage.handler.class.name' [WITH SERDEPROPERTIES (...)] -- (Note: Available in Hive 0.6.0 and later)
]
[LOCATION hdfs_path]
[TBLPROPERTIES (property_name=property_value, ...)] -- (Note: Available in Hive 0.6.0 and later)
[AS select_statement]; -- (Note: Available in Hive 0.5.0 and later; not supported for external tables)
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hive (default)> create table test(id int);
OK
Time taken: 10.143 seconds
获得表的建表语句
hive (default)> show create table test;
OK
createtab_stmt
CREATE TABLE `test`(
`id` int)
ROW FORMAT SERDE
'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe'
STORED AS INPUTFORMAT
'org.apache.hadoop.mapred.TextInputFormat'
OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
LOCATION
'hdfs://nameservice1/user/hive/warehouse/test'
TBLPROPERTIES (
'transient_lastDdlTime'='1436799093')
Time taken: 0.135 seconds, Fetched: 12 row(s)
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创建内部表
其他获得表的信息
创建外部表
hive (default)> create external table testexttable(
> name string comment 'name value',
> addr string comment 'addr value'
> );
OK
Time taken: 10.172 seconds
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create table if not exists testtable(
name string comment 'name value',
addr string comment 'addr value'
)
row format delimited fields terminated by '\t' lines terminated by '\n' stored as textfile
;
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加载数据
hive (default)> load data local inpath ‘/liguodong/hivedata/datatest’ overwrite into table testtable;
hive (default)> load data local inpath ‘/liguodong/hivedata/datatest’ into table testtable;
如果没有使用overwrite，则会再拷贝一份数据，不会覆盖原来的数据。
hive (default)> create external table if not exists employees(
> name string,
> salary string,
> subordinates array<string>,
> deductions map<string,float>,
> address struct<street:string,city:string,state:string,zip:int>
> )
> row format delimited fields terminated by '\t'
> collection items terminated by ','
> map keys terminated by ':'
> lines terminated by '\n'
> stored as textfile
> location '/liguodong/data/'
> ;
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查找表数据
hive> select * from employees;
OK
tony 1338 ["a1","a2","a3"] {"k1":1.0,"k2":2.0,"k3":3.0} {"street":"s1","city":"s2","state":"s3","zip":4}
mark 5453 ["a4","a5","a6"] {"k4":4.0,"k5":5.0,"k6":6.0} {"street":"s4","city":"s5","state":"s6","zip":6}
ivy 323 ["a7","a8","a9"] {"k7":7.0,"k8":8.0,"k9":9.0} {"street":"s7","city":"s8","state":"s9","zip":9}
Time taken: 10.204 seconds, Fetched: 3 row(s)
查树组
hive> select subordinates[1] from employees;
Total MapReduce CPU Time Spent: 2 seconds 740 msec
OK
a2
a5
a8
查map
hive> select deductions["k2"] from employees;
OK
2.0
NULL
NULL
Time taken: 75.812 seconds, Fetched: 3 row(s)
查结构体
hive> select address.city from employees;
Total MapReduce CPU Time Spent: 2 seconds 200 msec
OK
s2
s5
s8
Time taken: 75.311 seconds, Fetched: 3 row(s)
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注意：select * 不执行mapreduce，只进行一个本地的查询。
而select 某个字段 生成一个job，执行mapreduce。
select * from employees;
select * from employees limit 10;
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删除表
内部表删除，会连同hdfs存储的数据一同删除，而外部表删除，只会删除外部表的元数据信息。
hive (default)> drop table testtable;
OK
Time taken: 10.283 seconds
hive (default)> drop table testexttable;
OK
Time taken: 0.258 seconds
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Hive建表的其他方式
有一个表，创建另一个表
（只是复制了表结构，并不会复制内容。）
create table test3 like test2;
不需要执行mapreduce
hive> desc testtable;
OK
name string name value
addr string addr value
Time taken: 0.267 seconds, Fetched: 2 row(s)
hive> create table testtableNew like testtable;
OK
Time taken: 10.323 seconds
hive> desc testtableNew;
OK
name string name value
addr string addr value
Time taken: 0.135 seconds, Fetched: 2 row(s)
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从其他表查询，再创建表
（复制表结构的同时，把内容也复制过来了）
create table test2 as select name,addr from test1;
需要执行mapreduce
hive> create table testNewtable as select name,addr from testtable;
hive> desc testNewtable;
OK
name string
addr string
Time taken: 0.122 seconds, Fetched: 2 row(s)
hive> select * from testNewtable;
OK
liguodong cd
aobama lsj
Time taken: 10.226 seconds, Fetched: 4 row(s)
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