>>
>> Multicolumn BRIN is like GIN. Every column is indexed separately.
>> The order of the columns doesn't matter.
>
> Right. You can use one index to cover all columns; the position of the
> column in the index won't matter for a query that uses one column. The
> only reason to have multiple BRIN indexes on a single table is to have
> a different pages_per_range.
Thanks for the information, I've attached the patch updated to v2.
PJ