hive的数据导入与数据导出:(本地,云hdfs,hbase),列分隔符的设置

hive表的数据源有四种:

hbase

hdfs

本地

其他hive表

 

而hive表本身有两种:

内部表和外部表。

而hbase的数据在hive中,可以建立对应的外部表(参看hive和hbase整合)

 

内部表和外部表

区别:删除时,内部表删除hadoop上的数据;而外部表不删,其数据在外部存储,hive表只是查看数据的形式,看时从外部读入数据:

内部表:CREATETABLE tab(column1 STRING, column2 STRING);
外部表:用EXTERNAL 关键字,且必须在表结尾指定如下参数

CREATE EXTERNAL TABLE  tab

(column1 STRING,

column2 STRING

)

ROW FORMAT DELIMITED FIELDS TERMINATED BY’\t’

stored as textfile

location ‘hdfs://namenode/tmp/lmj/tab/’;

 

分隔符的指定

有两种方式

(1)DELIMITED方式:

ROW FORMAT DELIMITED

[FIELDS TERMINATED BY char]

[COLLECTION ITEMS TERMINATED BY char]

[MAP KEYS TERMINATED BY char]

[LINES TERMINATED BY char]

(2)SERDE方式:

SERDE serde_name [WITH SERDEPROPERTIES(property_name=property_value, property_name=property_value, …)]

其中,[ROW FORMAT DELIMITED]关键字,是设置建表时加载数据所支持的列分隔符;

如果没有指定 ROW FORMAT 或者 ROW FORMAT DELIMITED,则会自动使用自带的 SerDe。

另外,建表时,用户还要为表指定列,同时也会指定自定义的SerDe,Hive通过SerDe确定表的具体的列数据。

举例如下:

内部表

create table user_info (user_id int, cid string,ckid string, username string)
row format delimited
fields terminated by ‘\t’
lines terminated by ‘\n’;
外部表
CREATE EXTERNAL TABLE test_1(id INT, name STRING, citySTRING)
SORTED AS TEXTFILE
ROW FORMAT DELIMITED
FIELDS TERMINATED BY’\t’
LOCATION ‘hdfs://http://www.cnblogs.com/..’

文件存储格式

如上,用关键字[STORED AS file_format]设置加载数据的文件类型,默认采用[STORED AS TEXTFILE]。主要格式有

STORED AS

SEQUENCEFILE

| TEXTFILE

|RCFILE

|INPUTFORMATinput_format_classname

OUTPUTFORMAT            output_format_classname

其中用STORED AS TEXTFILE 存储纯文本文件。如果数据需要压缩,使用 STORED AS SEQUENCE 。Hive本身支持的文件格式只有:Text File,Sequence File。

 

数据导入与导出:

一.数据导入:

1.1导入内部表
(1)本地或者hdfs导入:
        LOAD DATA[LOCAL] INPATH ‘filepath’ [OVERWRITE] INTO TABLEtablename [PARTITION(partcol1=val1, partcol2=val2 …)]
区别是看有无关键字local,有local表示从本地路径导入,无local表示从hadoop(hbase或hdfs)导入。
导入的前提是目标表必须存在。如果无表要先建表,再导入:
        CREATE TABLE myword(idSTRING, counts INT, dt STRING) row formatdelimitedfields terminated by ‘\t’;
(2)用hive表的select结果导入

INSERT OVERWRITE TABLE T1 SELECT * FROMT2;

其中,INSERT OVERWRITE TABLE表示覆盖,删除原数据;

而INSERT into TABLE 表示增量的插入,不删除原数据。

另外,

删除表:drop table if exists T1;

清空表:truncate table T1;

 

1.2 导入外部表:
建表时直接指定数据源(不能指定本地文件,必须是hdfs路径):

(1)Hdfs上数据导入hive:

	CREATE EXTERNAL TABLE wizad_mdm_dev_lmj_edition_20141120 (
	cookie_id STRING,
	guid STRING
	)
	 ROWFORMAT DELIMITED
         FIELDSTERMINATEDBY ','
         LINESTERMINATEDBY '\n'
         storedas textfile
       	 LOCATION'/user/wizad/test/lmj/edition_compare/';

其中,也可以用全路径location’hdfs://namenode/user/wizad/test/lmj/edition_compare/’;

(2)Hbase上数据导入hive表:

先指定参数

SET mapred.job.queue.name=queue3;

SEThbase.client.scanner.caching=5000;

SEThbase.zookeeper.quorum=datanode06,datanode07,datanode08;

SET zookeeper.znode.parent=/hbase;

有map类型结构,建表时需要指明:

CREATE EXTERNAL TABLE lxw2 (

key string,

value map<STRING,STRING>

)

STORED BY’org.apache.hadoop.hive.hbase.HBaseStorageHandler’

WITH SERDEPROPERTIES(“hbase.columns.mapping” =”:key,fixeddim:”)

TBLPROPERTIES(“hbase.table.name”=”wizad_mdm_task_geely_hk_20141014”);

 

查询结果

SELECT KEY,dim_name,dim_value FROM lxw2

LATERAL VIEW explode(VALUE) myTable1AS dim_name,dim_value

–WHERE KEY = ‘000000054153796

 

这里,读取Hbase库的数据,可能会导入失败,因为scan时间过大,可以设置长时间

sethbase.regionserver.lease.period=180000;

hbase与本地表jion时,可能出现启动后,无限等待。原因:

二.数据导出:

三种导出:

(1)导出到其他hive表:

覆盖:INSERT OVERWRITE TABLE t1 select * from t2;

不覆盖:INSERT INTO TABLE t1 select * from t2;

注意hive不支持 子查询结果直接建表,如 create table t1 as select * from t2; 在hive中是错误的

(2)导出到本地,hdfs(有无local):

INSERT OVERWRITE [LOCAL]DIRECTORY directory1 select_statement1

这里注意:

导出本地时可以指定列分隔符,

而导出到hdfs上不可以使用hive默认\001(^A)

导入到hdfs上不能指定列的分隔符:

使用语句ROW FORMAT DELIMITEDFIELDS TERMINATED BY ‘,’ 会报错,不能识别。

代码如

INSERT OVERWRITE DIRECTORY’/user/wizad/tmp/mytest’

select * from wizad_mdm_dev_lmj_edition_insterest

因为hive导出到hdfs上,默认使用^A作为列分隔符,其对应着001。官方文档:Data written to the filesystem is serialized as text with columns separated by ^A。(所以,python中用line.split(‘\x01’)或者line.split(‘\001’)切分。)

但这样的数据在pig中无法读入,用’\001’或者’\\001’或者’^A’都无法读入。

解决办法:作为一个列整体读入后,在用STRSPLIT分隔按’\\001’(使用’^A’无效),可以返回一个元组类似((a,b)),pig代码如下

%default interestFlie/user/wizad/tmp/mytest/*

–无效interest_data =LOAD ‘$interestFlie’ USING PigStorage(‘\\001’)

–无效interest_data =LOAD ‘$interestFlie’ USING PigStorage(‘^A’)

interest_data = LOAD ‘$interestFlie’

AS(cookie_id:chararray

—  guid:chararray,

—  dimkey :chararray,

—  dimvalue:chararray

);

test2 = foreach interest_data generateSTRSPLIT(cookie_id,’\\001′);

DUMP res;

describe res;

结果:result结构:{(null)}

((B2BEF56E09EC115456E221,352751019523267,interest_11,161))

((B2BEF56E09EC115456E221,352751019523267,interest_13,102))

((EC15860E09D5EA545700E9,352751019523267,interest_11,161))

((EC15860E09D5EA545700E9,352751019523267,interest_13,102))

((daca0487-5424ef1a0dc3fa-11535481,352751019523267,interest_4,61))

((daca0487-5424ef1a0dc3fa-11535481,352751019523267,interest_21,21))

((daca0487-5424ef1a0dc3fa-11535481,352751019523267,interest_11,161))

((daca0487-5424ef1a0dc3fa-11535481,352751019523267,interest_13,102))

 

 

指定导出全路径也不行。

INSERT OVERWRITE DIRECTORY’hdfs://namenode/user/wizad/tmp/interest2/’

ROW FORMAT DELIMITED FIELDS TERMINATED BY’,’

select * fromwizad_mdm_dev_lmj_edition_insterest

 

2导出到本地,可以指定列分隔符:

INSERT OVERWRITE local DIRECTORY’/home/wizad/lmj/inserest2′

ROW FORMAT DELIMITED FIELDS TERMINATED BY’,’

select * fromwizad_mdm_dev_lmj_edition_insterest

 

导入到本地可直接用-e命令,默认使用\t分隔:

hive -e ‘use wizad;

select * fromwizad_mdm_dev_lmj_edition_insterest;’>> mytest

查询结果使用\t作为列分隔符,mytest中

3531 3631 3730 3631 3931 3635 34360969  51617061916546.i

vim中16进制(%!xxd)两位对应一个字符,看到”.”对应的09,在asii码表中09,就是tab制表符

 

也可以用hive -f:

[wyp@master ~/local]$ cat wyp.sql

select * from wyp

[wyp@master ~/local]$ hive -f wyp.sql>> local/wyp2.txt

 

 

http://blog.csdn.net/longshenlmj/article/details/41519503

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