Description
----------- 
You can defragment the query cache to better utilize its
memory with
the FLUSH QUERY CACHE statement. The statement does not
remove any queries from the cache.
 
The RESET QUERY CACHE statement removes all query results
from the query cache.
The FLUSH TABLES statement also does this.
 

 
 
 
 
 
 
 

URL: https://mariadb.com/kb/en/flush-query-cache/