If you want to see how long your database queries actually take, you need to disable MySQL's query cache. This can be done globally by logging into a database console, run
SET GLOBAL query_cache_type=OFF;
and restart your rails server.
You can also disable the cache on a per query basis by saying
SELECT SQL_NO_CACHE * FROM ...
You also probably want to disable Rails internal (per-request) cache. For this, wrap your code with a call to
ActiveRecord::Base.uncached. For example, as an
def disable_cache ActiveRecord::Base.uncached do yield end true end
Don't forget to re-enable MySQL query caching later with
SET GLOBAL query_cache_type=ON;