On Wed, Apr 19, 2023 at 7:35 AM Greg Stark <st...@mit.edu> wrote: > On Mon, 17 Apr 2023 at 17:45, Thomas Munro <thomas.mu...@gmail.com> wrote: > > (2) without a page cache, you really need to size your shared_buffers > > adequately and we can't do that automatically. > > Well.... I'm more optimistic... That may not always be impossible. > We've already added the ability to add more shared memory after > startup. We could implement the ability to add or remove shared buffer > segments after startup.
Yeah, there are examples of systems going back decades with multiple buffer pools. In some you can add more space later, and in some you can also configure pools with different block sizes (imagine if you could set your extremely OLTP tables to use 4KB blocks for reduced write amplification and then perhaps even also promise that your storage doesn't need FPIs for that size because you know it's perfectly safe™, and imagine if you could set some big write-only history tables to use 32KB blocks because some compression scheme works better, etc), and you might also want different cache replacement algorithms in different pools. Complex and advanced stuff no doubt and I'm not suggesting that's anywhere near a reasonable thing for us to think about now (as a matter of fact in another thread you can find me arguing for fully unifying our existing segregated SLRU buffer pools with the one true buffer pool), but since we're talking pie-in-the-sky ideas around the water cooler...
