On Fri, Feb 2, 2018 at 9:28 PM, David G. Johnston
> You probably can (I assume the nulls aspect of the index doesn't prevent PK
> usage), but you must add the PK to the table after creating the index and
> not let the system auto-generate the index for you.
> ALTER TABLE name ADD PRIMARY KEY USING INDEX index_name;
I missed to notice this in the docs. Thank you David for pointing it out.