Hi, On 2023-01-11 17:26:19 -0700, David G. Johnston wrote: > Should we just add "ring_buffers" to the existing "shared_buffers" and > "temp_buffers" settings?
The different types of ring buffers have different sizes, for good reasons. So I don't see that working well. I also think it'd be more often useful to control this on a statement basis - if you have a parallel import tool that starts NCPU COPYs you'd want a smaller buffer than a single threaded COPY. Of course each session can change the ring buffer settings, but still. > Then give VACUUM a (BUFFER_POOL=ring*|shared) option? That seems likely to mislead, because it'd still use shared buffers when the blocks are already present. The ring buffers aren't a separate buffer pool, they're a subset of the normal bufferpool. Lookup is done normally, only when a page isn't found, the search for a victim buffer first tries to use a buffer from the ring. > I think making DBAs aware of this dynamic and making the ring buffer usage > user-facing is beneficial in its own right (at least, the concept that > changes done by vacuum don't impact shared_buffers, regardless of how that > non-impact manifests). VACUUM can end up dirtying all of shared buffers, even with the ring buffer in use... Greetings, Andres Freund
