Re: BUG #18616: Long-running hash index build can not be interrupted

I wrote:
> Looking at hashbuild, the effective sort_threshold depends on
> NBuffers, so maybe if you have that set to a high enough value
> it fails to go into the sort path? If I use
> SET maintenance_work_mem = '128MB';
> instead of the suggested 1GB, I don't see the problem.

Oh, false alarm: that test in hashbuild takes basically the
min of maintenance_work_mem and NBuffers, so that with
default NBuffers of 128MB, there's no difference here between
those two settings.

The reason I see a difference in behavior seems to be that
with maintenance_work_mem = 1GB, the tuple sorting step
completes faster, allowing control to reach _h_indexbuild
before the 10sec timeout I was testing with. With the
smaller maintenance_work_mem setting, we're still sorting
when it times out --- and there are CHECK_FOR_INTERRUPTS
calls in the sort code.

regards, tom lane