If you are running on a Linux kernel, try /proc/sys/vm/drop_caches. I believe the appropriate command is "echo 3 > /proc/sys/vm/drop_caches". Since Postgres has its own cache of data, the above followed by a PG restart should do what you are looking for. Ranga > Barry Moore wrote: > >> I have a very slow query that I'm trying to tune. I think my >> performance tuning is being complicated by the system's page cache. >> >> If a run the query after the system has been busy with other tasks >> for quite a long time then the query can take up to 8-10 minutes to >> complete. If I then rerun the same query it will complete in a >> couple of seconds. >> >> Does anyone know how I can repeatedly run the same query in the >> "worst case scenario" of no postgres data in the disk cache (e.g., >> clear the page cache or force it to be ignored)? > > In my experience the only 100% reliable way to do this is to reboot the > machine. > > > > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq >
