I have a SP which include a group by SQL statement. It retrieve data from a couple of tables which are over 1G size,
When I run this SP at first time, it take more than 5 minutes to get the result. then I run it again and again, Finally, it become very quick, I can get the result within second.
Not sure why. I guess it is because of query plan.
How to make it running at first time to get result within second? How to force a better best query plan in effective at first time to run the query?
If the engine has better plan in memory, could it be lost at some point? because I have the complain from end user said some times it is fast, sometime it is very slow.
How to resolve this problem?