Re: Add bms_offset_members() function for bitshifting Bitmapsets

David Rowley <dgrowleyml@gmail.com> writes:
> On Wed, 15 Apr 2026 at 12:29, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I question the decision to make this change the set in-place.
>> Wouldn't it be cheaper and less surprise-prone to always make
>> a copy?

> I'd not considered surprise-prone as an aspect. I understand we have
> bms_join and bms_union, which do the same thing if you only care about
> the value of the result and not what happens to the inputs.

Sure, but bms_join is an optional optimization of the far safer
bms_union operation.  It bothers me to create the optimized case
but not the base case.

            regards, tom lane