replace() using NULL

Hello,

tested by using postgresql 13.5:

SELECT REPLACE('xyz‘, ’y’, ’a’); => xaz => expected
SELECT REPLACE('xyz', 'a‘, 'b‘); => xyz => expected

SELECT REPLACE('xyz‘, 'a‘, NULL); => NULL

Also tested by using MariaDB. Same behavior like in PG.
Tested with Oracle, result is ‚xyz‘.

That is what I would expect because xyz includes no a.

I neither can find any documentation about this nor a bug report.

Regards,

miracee (Susanne)