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1.问题 hive中增加字段 发现之后之后添加的数据正常，之前数据无法读取
问题修复：
查找hive元数据的分区字段边 SDS
MySQL [hive]> SELECT * FROM SDS WHERE location LIKE '%video_test%' ;
+--------+-------+------------------------------------------+---------------+---------------------------+--------------------------------------------------------------------------------+-------------+------------------------------------------------------------+----------+
| SD_ID | CD_ID | INPUT_FORMAT | IS_COMPRESSED | IS_STOREDASSUBDIRECTORIES | LOCATION | NUM_BUCKETS | OUTPUT_FORMAT | SERDE_ID |
+--------+-------+------------------------------------------+---------------+---------------------------+--------------------------------------------------------------------------------+-------------+------------------------------------------------------------+----------+
| 153927 | 1580 | org.apache.hadoop.mapred.TextInputFormat | | | hdfs://cluster1/video_test/daily/2018/03/01 | -1 | org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat | 153927 |
| 154297 | 1580 | org.apache.hadoop.mapred.TextInputFormat | | | hdfs://cluster1/video_test/daily/2018/03/02 | -1 | org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat | 154297 |
| 154529 | 1580 | org.apache.hadoop.mapred.TextInputFormat | | | hdfs://cluster1/video_test//daily/2017/12/20 | -1 | org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat | 154529 |
.....
| 180211 | 2880 | org.apache.hadoop.mapred.TextInputFormat | | | hdfs://cluster1/video_test/daily/2018/04/26 | -1 | org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat | 180211 |
发现 分区正常的CD_ID 和不正常的CD_ID 是不一样的
修改问同样问题即可解决
UPDATE SDS SET CD_ID=‘2880’ where CD_ID=‘1580’;（操作不当可能损坏元数据）
2.当然也可以删除分区重新add partition (外部表) 风险低 分区多比较麻烦
如果分区路径和分区信息一致 也可尝试msck repair table tablename;(可能导致分区错乱)
3.最简单的办法， 使用CASCADE及联 强制
alter table tablename add columns (cl1name string COMMENT 'cl1',cl2name string COMMENT 'cl2') CASCADE;