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1.问题描述
通过sqoop抽取Mysql表数据到hive表,发现hive表所有列显示为null
Hive表的分隔符为“u001B”,sqoop指定的分隔符也是“u001B”
通过命令show create table test_hive_delimiter查看建表语句如下:
0: jdbc:hive2://localhost:10000/> show create table test_hive_delimiter;
...
INFO : OK
+----------------------------------------------------+--+
| createtab_stmt |
+----------------------------------------------------+--+
| CREATE EXTERNAL TABLE `test_hive_delimiter`( |
| `id` int, |
| `name` string, |
| `address` string) |
| ROW FORMAT SERDE |
| 'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe' |
| WITH SERDEPROPERTIES ( |
| 'field.delim'='\u0015', |
| 'serialization.format'='\u0015') |
| STORED AS INPUTFORMAT |
| 'org.apache.hadoop.mapred.TextInputFormat' |
| OUTPUTFORMAT |
| 'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat' |
| LOCATION |
| 'hdfs://ip-172-31-6-148.fayson.com:8020/fayson/test_hive_delimiter' |
| TBLPROPERTIES ( |
| 'COLUMN_STATS_ACCURATE'='false', |
| 'numFiles'='0', |
| 'numRows'='-1', |
| 'rawDataSize'='-1', |
| 'totalSize'='0', |
| 'transient_lastDdlTime'='1504705887') |
+----------------------------------------------------+--+
22 rows selected (0.084 seconds)
0: jdbc:hive2://localhost:10000/>
发现Hive的原始建表语句中的分隔符是“u001B”而通过show create table test_hive_delimiter命令查询出来的分隔符为“u0015”,分隔符被修改了。
2.问题复现
1.创建Hive表test_hive_delimiter,使用“u001B”分隔符
create external table test_hive_delimiter
(
id int,
name string,
address string
)
row format delimited fields terminated by '\u001B'
stored as textfile location '/fayson/test_hive_delimiter';
2.使用sqoop抽取MySQL中test表数据到hive表(test_hive_delimiter)
[root@ip-172-31-6-148 ~]# sqoop import --connect jdbc:mysql://ip-172-31-6-148.fayson.com:3306/fayson -username root -password 123456 --table test -m 1 --hive-import --fields-terminated-by "\0x001B" --target-dir /fayson/test_hive_delimiter --hive-table test_hive_delimiter
数据抽取成功:
[root@ip-172-31-6-148 ~]# hadoop fs -ls /fayson/test_hive_delimiter
Found 2 items
-rw-r--r-- 3 fayson supergroup 0 2017-09-06 13:46 /fayson/test_hive_delimiter/_SUCCESS
-rwxr-xr-x 3 fayson supergroup 56 2017-09-06 13:46 /fayson/test_hive_delimiter/part-m-00000
[root@ip-172-31-6-148 ~]# hadoop fs -ls /fayson/test_hive_delimiter/part-m-00000
-rwxr-xr-x 3 fayson supergroup 56 2017-09-06 13:46 /fayson/test_hive_delimiter/part-m-00000
[root@ip-172-31-6-148 ~]#
3.查看test_hive_delimiter表数据
[root@ip-172-31-6-148 ~]# beeline
Beeline version 1.1.0-cdh5.12.1 by Apache Hive
beeline> !connect jdbc:hive2://localhost:10000/;principal=hive/ip-172-31-6-148.fayson.com@FAYSON.COM
...
Transaction isolation: TRANSACTION_REPEATABLE_READ
0: jdbc:hive2://localhost:10000/> select * from test_hive_delimiter;
...
INFO : OK
+-------------------------+---------------------------+------------------------------+--+
| test_hive_delimiter.id | test_hive_delimiter.name | test_hive_delimiter.address |
+-------------------------+---------------------------+------------------------------+--+
| NULL | NULL | NULL |
| NULL | NULL | NULL |
| NULL | NULL | NULL |
+-------------------------+---------------------------+------------------------------+--+
3 rows selected (0.287 seconds)
0: jdbc:hive2://localhost:10000/>
4.Hive表的建表语句如下
3.解决方法
分隔符“u001B”为十六进制,而Hive的分隔符实际是八进制,所以在使用十六进制的分隔符时会被Hive转义,所以出现使用“u001B”分隔符创建hive表后显示的分隔符为“u0015”。
在不改变数据文件分隔符的情况下,要先将十六进制分隔符转换成八进制分隔符来创建Hive表。
1.将十六进制分隔符转换为八进制分隔符
“u001B”转换八进制为“033”,在线转换工具:http://tool.lu/hexconvert/
2.修改建表语句使用八进制“033”作为分隔符
create external table test_hive_delimiter
(
id int,
name string,
address string
)
row format delimited fields terminated by '\033'
stored as textfile location '/fayson/test_hive_delimiter';
使用命令show create table test_hive_delimiter查看建表语句
0: jdbc:hive2://localhost:10000/> show create table test_hive_delimiter;
...
INFO : OK
+----------------------------------------------------+--+
| createtab_stmt |
+----------------------------------------------------+--+
| CREATE EXTERNAL TABLE `test_hive_delimiter`( |
| `id` int, |
| `name` string, |
| `address` string) |
| ROW FORMAT SERDE |
| 'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe' |
| WITH SERDEPROPERTIES ( |
| 'field.delim'='\u001B', |
| 'serialization.format'='\u001B') |
| STORED AS INPUTFORMAT |
| 'org.apache.hadoop.mapred.TextInputFormat' |
| OUTPUTFORMAT |
| 'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat' |
| LOCATION |
| 'hdfs://ip-172-31-6-148.fayson.com:8020/fayson/test_hive_delimiter' |
| TBLPROPERTIES ( |
| 'COLUMN_STATS_ACCURATE'='false', |
| 'numFiles'='0', |
| 'numRows'='-1', |
| 'rawDataSize'='-1', |
| 'totalSize'='0', |
| 'transient_lastDdlTime'='1504707693') |
+----------------------------------------------------+--+
22 rows selected (0.079 seconds)
0: jdbc:hive2://localhost:10000/>
3.查询test_hive_delimiter表数据
0: jdbc:hive2://localhost:10000/> select * from test_hive_delimiter;
...
INFO : OK
+-------------------------+---------------------------+------------------------------+--+
| test_hive_delimiter.id | test_hive_delimiter.name | test_hive_delimiter.address |
+-------------------------+---------------------------+------------------------------+--+
| 1 | fayson | guangdong |
| 2 | zhangsan | shenzheng |
| 3 | lisi | shanghai |
+-------------------------+---------------------------+------------------------------+--+
3 rows selected (0.107 seconds)
0: jdbc:hive2://localhost:10000/>
将十六进制的”u001B”转换为八进制的”033”建表,问题解决。
4.备注
- Hive建表时使用十六进制分割符需要注意,部分分隔符会被转义(如:001B/001C等)
- Sqoop指定十六进制分隔符,为什么是“0x001B”而不是“u001B”,可参考Sqoop
官网说明:https://sqoop.apache.org/docs/1.4.6/SqoopUserGuide.html#_file_formats
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