On Thu, Jun 15, 2023 at 1:37 PM Vladimir Churyukin <vladi...@churyukin.com> wrote: > Ok, got it, thanks. > Is there any alternative approach to measuring the performance as if the > cache was empty?
There are two levels of cache. If you're on Linux you can ask it to drop its caches by writing certain values to /proc/sys/vm/drop_caches. For PostgreSQL's own buffer pool, it would be nice if someone would extend the pg_prewarm extension to have a similar 'unwarm' operation, for testing like that. But one thing you can do is just restart the database cluster, or use pg_prewarm to fill its buffer pool up with other stuff (and thus kick out the stuff you didn't want in there).
