Last night I was doing some tuning on a database The longest query I was running was taking around 160 seconds. I didn't see much change in the running time for that query, even after restarting PG.
Today, with roughly the same system load (possibly even a bit heavier load), that query is running about 40 seconds.
Are there tuning parameters in postgresql.conf that don't take effect right away, even after a restart of PG? The only thing I can come up that's happened since last night was that we ran the nightly vacuum analyze on that database, but I did not change the statistics target.
The parameters I was working with were:
effective_cache_size
shared_buffers
temp_buffers
work_mem
maintenance_work_mem
Looking at the free command, I see a lot more memory being used for buffer/cache today. (Centos 7.)
