On Thu, Jan 12, 2023 at 6:06 AM Andres Freund <and...@anarazel.de> wrote: > > 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.
How about having GUCs for each ring buffer (bulk_read_ring_buffers, bulk_write_ring_buffers, vacuum_ring_buffers - ah, 3 more new GUCs)? These options can help especially when statement level controls aren't easy to add (COPY, CREATE TABLE AS/CTAS, REFRESH MAT VIEW/RMV)? If needed users can also set them at the system level. For instance, one can set bulk_write_ring_buffers to other than 16MB or -1 to disable the ring buffer to use shared_buffers and run a bunch of bulk write queries. Although I'm not quite opposing the idea of statement level controls (like the VACUUM one proposed here), it is better to make these ring buffer sizes configurable across the system to help with the other similar cases e.g., a CTAS or RMV can help subsequent reads from shared buffers if ring buffer is skipped. Thoughts? -- Bharath Rupireddy PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
