Hi, A way to trick EXPLAIN/EXPLAIN ANALYZE to do what you mean is to play with the optimisation variables:
https://www.postgresql.org/docs/9.6/static/runtime-config-query.html J. On 25 November 2017 at 15:01, Adam Tauno Williams <awill...@whitemice.org> wrote: > On Fri, 2017-11-24 at 11:58 -0800, John R Pierce wrote: >> On 11/24/2017 11:43 AM, Michael Nolan wrote: >> > There are so many different levels of caching going on--within >> > Postgresql, within the OS, within a disk array or SAN, and at the >> > individual drive--that there may no longer be a meaningful way to >> > perform this measurement. >> generally, power cycling the server will flush all the hardware >> caches AND the OS cache. > > Given that a real-world application will almost never experience an > empty-cache scenario I question the usefulness of clearing the > cache(s). I would capture transactions from a production database in > order to create a load test that mimics real-world load. > > -- > Meetings Coordinator, Michigan Association of Railroad Passengers > 537 Shirley St NE Grand Rapids, MI 49503-1754 Phone: 616.581.8010 > E-mail: awill...@whitemice.org GPG#D95ED383 Web: http://www.marp.org > -- Jerome Eteve http://www.justgiving.com/jetevesober +44(0)7738864546 http://www.eteve.net/
