postgres=# select 1=1;
 ?column? 
----------
 t
(1 row)

postgres=# select null=null
postgres-# ;
 ?column? 
----------
 
(1 row)

postgres=# select 1==1
postgres-# ;
ERROR:  operator does not exist: integer == integer
LINE 1: select 1==1
                ^
HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
postgres=# create extension fulleq;
CREATE EXTENSION
postgres=# select 1==1
;
 ?column? 
----------
 t
(1 row)

postgres=# select null==null;
 ?column? 
----------
 t
(1 row)

postgres=# select null==2;
 ?column? 
----------
 f
(1 row)

postgres=# select null=2;
 ?column? 
----------
 
(1 row)