hive null parse

Sqoop

--null-string ''   \
--null-non-string ''  \

Hive

Method 1：

alter table ...  set serdeproperties ('serialization.null.format' = "");

Method 2：

TBLPROPERTIES('serialization.null.format' = "") ;  

Test examples

drop table if exists test; 
CREATE EXTERNAL TABLE test ( 
uuid               string,                                  
user_id            bigint                           
) 
row format delimited fields terminated by '\t' 
LOCATION '/AidenSun/test'   
TBLPROPERTIES('serialization.null.format' = "") ;   
 
 insert into test values("1","");
 
hive>  select * from test;
OK
1	NULL

select  coalesce(user_id,uuid) as user_id from test;
	

Files in HDFS：

Spark
如果上面的hive表是parquet表，必须确保dataframe不会产生新的“” ,否则hive上述设置失效。

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