Re: negative bitmapset member not allowed Error with partition pruning

Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com> writes:
> I am getting "ERROR: negative bitmapset member not allowed" when
> enable_partition_pruning set to true with below test case.

Confirmed here. It's failing in perform_pruning_combine_step,
which reaches this:

result->bound_offsets = bms_add_range(NULL, 0, boundinfo->ndatums - 1);

with boundinfo->ndatums == 0. It's not clear to me whether that situation
should be impossible or not. If it is valid, perhaps all we need is
something like

if (boundinfo->ndatums > 0)
result->bound_offsets = bms_add_range(NULL, 0, boundinfo->ndatums - 1);
else
result->bound_offsets = NULL;

although that then opens the question of whether downstream code is
OK with bound_offsets being empty.

(BTW, I'm not sure that it was wise to design bms_add_range to fail for
empty ranges. Maybe it'd be better to redefine it as a no-op for
upper < lower?)

regards, tom lane