Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> writes:
> Another idea could be each index AM tell whether it uses
> maintainence_work_mem or not and based on that we can do the
> computation (divide the maintainence_work_mem by the number of such
> indexes during parallel vacuum).
FWIW, that seems like a perfectly reasonable API addition to me.
regards, tom lane