Re: [PoC] Improve dead tuple storage for lazy vacuum

> > Looking at other code using DSA such as tidbitmap.c and nodeHash.c, it
> > seems that they look at only memory that are actually dsa_allocate'd.
> > To be exact, we estimate the number of hash buckets based on work_mem
> > (and hash_mem_multiplier) and use it as the upper limit. So I've
> > confirmed that the result of dsa_get_total_size() could exceed the
> > limit. I'm not sure it's a known and legitimate usage. If we can
> > follow such usage, we can probably track how much dsa_allocate'd
> > memory is used in the radix tree.
>
> I've experimented with this idea. The newly added 0008 patch changes
> the radix tree so that it counts the memory usage for both local and
> shared cases. As shown below, there is an overhead for that:
>
> w/o 0008 patch
>      298453544 |     282

> w/0 0008 patch
>      293603184 |     297