Re: BAS_BULKREAD vs read stream - Mailing list pgsql-hackers

On Sun, Apr 6, 2025 at 4:15 PM Andres Freund <andres@anarazel.de> wrote:
>
> I think we should consider increasing BAS_BULKREAD TO something like
>   Min(256, io_combine_limit * (effective_io_concurrency + 1))

Do you mean Max? If so, this basically makes sense to me.
Overall, I think even though the ring is about reusing buffers, we
have to think about how many IOs that reasonably is -- which this
formula does.

You mentioned testing with 8MB, did you see some sort of clipp
anywhere between 256 and 8MB?

> I experimented some whether SYNC_SCAN_REPORT_INTERVAL should be increased, and
> couldn't come up with any benefits. It seems to hurt fairly quickly.

So, how will you deal with it when the BAS_BULKREAD ring is bigger?

- Melanie