hive操作

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)

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;

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)