Temporarily turn off MySQL cache

We often optimize SQL Have you ever encountered this kind of situation ？？

There is a query that takes a long time SQL, First query , The time spent is normal , Query again , It takes a lot less time ,, What's going on here ？？

This is because MySQL There is a cache , Once executed, there is a cache , So the time to query again becomes very short , We can temporarily turn off the cache to verify SQL Whether the optimization is successful .

set global query_cache_size=0; 
set global query_cache_type=0;

The cache will be restarted after restart