Subject Re: [ib-support] Index on Boolean-Col
> No! this index would have the lowest possible selectivity, rendering it a Trojan Horse for performance.
> Are you saying you want to ORDER BY this Boolean-style column (i.e. all the FALSE ones first?) Or do you want to combine it with another column?

No, I just want to order by this column.

Just for me to remember, selectivity is (1 / count of unique values) ?
And what does selectivity exactly mean and what it is used for ?