On Fri, Dec 8, 2023 at 11:24 PM Alexander Korotkov <aekorotkov@gmail.com> wrote:
>
> Hi, Ashutosh!
>
> On Fri, Dec 8, 2023 at 3:28 PM Ashutosh Bapat
> <ashutosh.bapat.oss@gmail.com> wrote:
> > I did some analysis of memory consumption by bitmapsets in such cases.
> > [1] contains slides with the result of this analysis. The slides are
> > crude and quite WIP. But they will give some idea.
> >
> > [1] https://docs.google.com/presentation/d/1S9BiAADhX-Fv9tDbx5R5Izq4blAofhZMhHcO1c-wzfI/edit?usp=sharing
>
> Thank you for sharing your analysis. I understand that usage of a
> plain bitmap becomes a problem with a large number of partitions. But
> I wonder what does "post proposed fixes" mean? Is it the fixes posted
> in [1]. If so it's very surprising for me they are reducing the
> memory footprint size.
No. These are fixes in various threads all listed together in [1]. I
had started investigating memory consumption by Bitmapsets around the
same time. The slides are result of that investigation. I have updated
slides with this reference.
[1] https://www.postgresql.org/message-id/CAExHW5s_KwB0Rb9L3TuRJxsvO5UCtEpdskkAeMb5X1EtssMjgg@mail.gmail.com
They reduce the memory footprint by Bitmapset because they reduce the
objects that contain the bitmapsets, thus reducing the total number of
bitmapsets produced.
--
Best Wishes,
Ashutosh Bapat