Bug / Unexpected behaviour of NOT LIKE

Hi,

I believe that I have found a bug or at least an undocumented unexpected behaviour in the NOT LIKE operator (tested in PG 13). Namely, the query 

SELECT * FROM users WHERE comment NOT LIKE 'hello%'; 

never returns any users where the comment cell is empty, even though empty also isn't "hello%". This caused bugs in several parts of my code and there is nothing about it in the documentation of the LIKE operator.

If this is intended behaviour, I believe that it deserves a big warning note in the documentation: all occasions where someone might reasonably use NOT LIKE should be combined with a IS NULL OR, i.e. "comment IS NULL OR comment NOT LIKE 'hello%'"

Best wishes,

Judith Meyer

>>DiEM25