Hive过滤脏数据的一些经验
如下文件需要处理，每个文件大概13G，其中字段以空格（32）分隔的7个字段；最麻烦的是中间有脏数据：
-rw-r--r-- 1 hadoop ifengdev 1895843464 May 6 14:56 feedback201503_201.tar.gz -rw-r--r-- 1 hadoop ifengdev 1896885848 May 6 14:59 feedback201503_202.tar.gz -rw-r--r-- 1 hadoop ifengdev 1891790676 May 6 15:00 feedback201503_203.tar.gz -rw-r--r-- 1 hadoop ifengdev 1894197100 May 6 15:01 feedback201503_204.tar.gz -rw-r--r-- 1 hadoop ifengdev 1894074074 May 6 15:02 feedback201503_205.tar.gz -rw-r--r-- 1 hadoop ifengdev 1829224750 May 6 16:13 feedback201504_201.tar.gz -rw-r--r-- 1 hadoop ifengdev 1831709571 May 6 16:14 feedback201504_202.tar.gz -rw-r--r-- 1 hadoop ifengdev 1824710879 May 6 16:30 feedback201504_203.tar.gz -rw-r--r-- 1 hadoop ifengdev 1827164031 May 6 16:31 feedback201504_204.tar.gz -rw-r--r-- 1 hadoop ifengdev 1827911208 May 6 16:31 feedback201504_205.tar.gz
直接Load进Hive报错：
Loading data to table default.tmp_20150506 Failed with exception Wrong file format. Please check the file's format. FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.MoveTask
没办法中间格式有问题：
网上说改变存储格式可以避免报错：
CREATE TABLE tmp_20150506( dt string, unknown1 string, unknown2 string, reurl string, uid string, num1 int, num2 int) ROW FORMAT DELIMITED FIELDS TERMINATED BY '32' LINES TERMINATED BY '10' STORED AS INPUTFORMAT 'org.apache.hadoop.hive.ql.io.RCFileInputFormat' OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.RCFileOutputFormat' 改为： CREATE TABLE tmp_20150506( dt string, unknown1 string, unknown2 string, reurl string, uid string, num1 int, num2 int) ROW FORMAT DELIMITED FIELDS TERMINATED BY '32' LINES TERMINATED BY '10' STORED AS TEXTFILE;
确实不报错了，根据具体需求也算一个方法；
最直接的方法：
zcat feedback201503_201.tar.gz|gawk -F ' ' 'NF==7 {print $1, "\t", $2, "\t", $3, "\t", $4, "\t", $5, F ' ' 'NF==7 {print $1, "\t", $2, "\t", $3, "\t", $4, "\t", $5, "\t", $6, "\t", $7}' >> feedback20150, "\t", $6, "\t", $7}' >> feedback201503_204.log
功能：替换空格为制表符；并且过滤字段不满足要求的脏数据；
接着Load进Hive即可；
上述方法比较直接，但觉得“体力劳动“过多，可能我比较懒，所以相对喜欢下边的方法：
基本思路就是把一行作为一个字段load进Hive，利用Hive本身筛选数据：
CREATE TABLE tmp_20150506_raw( allfilds string ) ROW FORMAT DELIMITED FIELDS TERMINATED BY '10' LINES TERMINATED BY '10' STORED AS TEXTFILE;
FIELDS TERMINATED BY '10'
LINES TERMINATED BY '10'
都设置成换行符即可，进入Hive以后使用Hive筛选数据即可。
筛选数据并存入另外一张表中，本例的后续处理过程如下：
from ( from ( select allfilds from tmp_20150506_raw where size(split(allfilds, ' ')) = 7) a select split(allfilds, ' ')[0] as dt, split(allfilds, ' ')[1] as unknown1, split(allfilds, ' ')[2] as unknown2, split(allfilds, ' ')[3] as reurl, split(allfilds, ' ')[4] as uid, split(allfilds, ' ')[5] as num1, split(allfilds, ' ')[6] as num2) b insert overwrite table tmp_20150506 partition(month = '2015-04') select *
