5 ms·
When you say cold cache, did you clear the os page cache as well as the postgres buffercaches? After setup.sql, the cache will be warmish - I get 4ms on the fir
by ethanseal 1y ago
When you say cold cache, did you clear the os page cache as well as the postgres buffercaches? After setup.sql, the cache will be warmish - I get 4ms on the first run. I'm using postgres 17.5
See https://github.com/ethan-seal/ors_expensive/blob/main/benchmark.sh https://github.com/ethan-seal/ors_expensive/blob/main/benchm... where I use dd to clear the os page cache.
This article by pganalyze talks about it: https://pganalyze.com/blog/5mins-postgres-17-pg-buffercache-evict https://pganalyze.com/blog/5mins-postgres-17-pg-buffercache-...
- hans_castorp 1y agoI did not explicitly evict the Postgres buffer cache, but using pg_buffercache to evict all buffers for the table, yields a runtime of 23ms for me (still going for the BitmapOr). https://notebin.de/?ac3fcf55e6850f47#ERXndRrqp3X4zEWX5EC3dZUwdXzYhJd7QssK4dnSH3Kh https://notebin.de/?ac3fcf55e6850f47#ERXndRrqp3X4zEWX5EC3dZU... Which plan does Postgres choose in your case that results 100ms?
- ethanseal 1y agoExactly the same one from what I see: https://github.com/ethan-seal/ors_expensive/blob/main/explain_plans/cold_or_explain_plan https://github.com/ethan-seal/ors_expensive/blob/main/explai... Given the buffer reads seem close to yours, I believe it's page cache.