I'd like to clear the PostgreSQL cache (e.g. for benchmarking purposes). And I'd like to preload all tuples of a table (say mytable_one) into the cache.
AFAIK there is no way to force all caches to be cleared in PostgreSQL with an SQL command. The only way to achieve this, seems to restart PG (server), which is neither an option for benchmarking purposes nor for production.
But: 1. Isn't it possible to achieve a kind-of cache clearing (in a reliable way) by simply doing a "select * from mytable_two" given mytable_two is at least as large as mytable_one (which is the one we want to benchmark)?
2. I assume that "select * from mytable_one" loads as much of the tuples as it can into the cache. Are there better ways for preloading the contents of a table?