On Mon, Mar 29, 2021 at 11:10 AM Campbell, Lance <lance@illinois.edu> wrote:
> If you divide 451 by 21 you get 21.4 . I would have expected to see an average size greater than 24 MB. This
impliesto me that PostgreSQL is creating temp files that are smaller than 24 MB.
>
> What am I not understanding?
work_mem limits the in-memory space used by sort and hash operations.
It doesn't necessarily follow that the on-disk footprint is exactly
(or even approximately) the same as the in-memory footprint for any
given operation that barely can't fit in memory. The precise space
overheads will vary based on lots of factors, most of which are
implementation details.
--
Peter Geoghegan
