1.11-1.12 Sqoop导入数据时两种增量方式导入及direct

## query
有一个唯一标识符，通常这个表都有一个字段，类似于插入时间createtime    
where createtime => 20150924000000000 and createtime < 20150925000000000


##sqoop参数
Incremental import arguments:
   --check-column <column>            Source column to check for incremental change
   --incremental <import-type>        Define an incremental import of type ‘append‘ or ‘lastmodified‘
   --last-value <value>                   Last imported value in the incremental check column

##
bin/sqoop import --connect jdbc:mysql://hadoop-senior.ibeifeng.com:3306/test --username root --password 123456 --table my_user --target-dir /user/root/sqoop/imp_my_incr --num-mappers 1 --incremental append --check-column id --last-value 4  


#--incremental append       //追加方式
#--check-column        //检查的字段
#--last-value        //最后的值，不包含这个值，从这个值后面的开始导入


##
[root@hadoop-senior hadoop-2.5.0-cdh5.3.6]# bin/hdfs dfs -text /user/root/sqoop/imp_my_incr/part-m-00000
5,test,test
6,pudong,pudong
7,qiqi,qiqi

##
bin/sqoop import --connect jdbc:mysql://hadoop-senior.ibeifeng.com:3306/test --username root --password 123456 --table my_user --target-dir /user/root/sqoop/imp_my_incr --num-mappers 1 --delete-target-dir --direct