Hive Null Timestamp comparison not works properly

[#1]

Hi,

I have below Hive query and its not giving me "equals" as output. Why?

hive> select case when (NULL=NULL) then "equals" else "not equals" end as value;
OK
not equals

[#2]

@Gnanasekaran G Use the following ( <=>) operator instead of (=) operator

SELECT CASE WHEN (NULL<=>NULL) THEN "equals" ELSE "not equals" end AS value;

Reference:

https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF#LanguageManualUDF-RelationalOper...

[#3]

@Gnanasekaran G if this helped, please vote/accept best answer. we can close the thread

[#4]

(NULL=NULL) is neither true nor false it will evaluate to NULL/UNKNOWN. (reference https://www.simple-talk.com/sql/learn-sql-server/sql-and-the-snare-of-three-valued-logic/)

As pointed by @Murali Ramasami above you should use <=> operator if you would like null=null evaluate to true.