Re: Should we increase the default vacuum_cost_limit?

Julien Rouhaud <rjuju123(at)gmail(dot)com> writes:
> On Sat, Mar 9, 2019 at 10:04 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> 2. It's always bugged me that we don't allow fractional unit
>> specifications, say "0.1GB", even for GUCs that are integers underneath.
>> That would be a simple additional change on top of this, but I didn't
>> do it here.

> It annoyed me multiple times, so +1 for making that happen.

The first patch below does that, but I noticed that if we just do it
without any subtlety, you get results like this:

regression=# set work_mem = '30.1GB';
SET
regression=# show work_mem;
work_mem
------------
31562138kB
(1 row)

The second patch is a delta that rounds off to the next smaller unit
if there is one, producing a less noisy result:

regression=# set work_mem = '30.1GB';
SET
regression=# show work_mem;
work_mem
----------
30822MB
(1 row)

I'm not sure if that's a good idea or just overthinking the problem.
Thoughts?

regards, tom lane