On Sat, Apr 11, 2020 at 1:55 AM Robert Haas <robertmh...@gmail.com> wrote: > On Thu, Apr 9, 2020 at 1:46 AM Thomas Munro <thomas.mu...@gmail.com> wrote: > > The attached highly experimental patch adds a new GUC > > dynamic_shared_memory_main_size. If you set it > 0, it creates a > > fixed sized shared memory region that supplies memory for "fast" DSM > > segments. When there isn't enough free space, dsm_create() falls back > > to the traditional approach using eg shm_open(). > > I think this is a reasonable option to have available for people who > want to use it. I didn't want to have parallel query be limited to a > fixed-size amount of shared memory because I think there are some > cases where efficient performance really requires a large chunk of > memory, and it seemed impractical to keep the largest amount of memory > that any query might need to use permanently allocated, let alone that > amount multiplied by the maximum possible number of parallel queries > that could be running at the same time. But none of that is any > argument against giving people the option to preallocate some memory > for parallel query.
That all makes sense. Now I'm wondering if I should use exactly that word in the GUC... dynamic_shared_memory_preallocate?
