Lester,

> > A typo for sure; there's no such thing as a "non-nullable index".
>
> No. You can have an index on a column that has NULL entries, they just get grouped
> together.

Still there is no such thing as a "non-nullable index"; constraints
apply to the columns, indexes just happen to "inherit" them.
Just a matter of terminology, I suppose.
Ciao
--
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_/\/ando