Does the MultiDelimitSerde support NULL DEFINED AS clause? - sql

Question

This article shows that we can use multi-character delimiter in Hive.
But can we also specify the NULL value?
I tried the following hive sql which returns an error:
CREATE TABLE temp
( a STRING, b STRING)
ROW FORMAT SERDE 'org.apache.hadoop.hive.contrib.serde2.MultiDelimitSerDe'
WITH SERDEPROPERTIES ("field.delim"="##")
NULL DEFINED AS 'NULL'
STORED AS TEXTFILE;
The error:
Error: Error while compiling statement: FAILED: ParseException line 5:0 missing EOF at 'NULL' near ')' (state=42000,code=40000)

Answer 1

The option to use NULL DEFINED AS 'NULL' is available when we are using a ROW FORMAT DELIMITED option. Here we are using a ROW FORMAT SERDE option so we need to explicitly pass the property serialization.null.format.
you can use the below query by setting the property value of serialization.null.format:
CREATE TABLE temp
( a STRING, b STRING)
ROW FORMAT SERDE 'org.apache.hadoop.hive.contrib.serde2.MultiDelimitSerDe'
WITH SERDEPROPERTIES ("field.delim"="##",'serialization.null.format'='NULL')
STORED AS TEXTFILE;
For more information you can refer Hive DDL reference guide. MultiDelimitSerde source code.
HIVE DDL GUIDE:
row_format
: DELIMITED [FIELDS TERMINATED BY char [ESCAPED BY char]] [COLLECTION ITEMS TERMINATED BY char]
[MAP KEYS TERMINATED BY char] [LINES TERMINATED BY char]
[NULL DEFINED AS char] -- (Note: Available in Hive 0.13 and later)
| SERDE serde_name [WITH SERDEPROPERTIES (property_name=property_value, property_name=property_value, ...)]