You can check whether the query cache is present in your MySQL server using the following statement:
mysql> SHOW VARIABLES LIKE 'have_query_cache';
You can defragment the query cache to better utilize its memory with
FLUSH QUERY CACHE
RESET QUERY CACHE
statement removes all query results from the query cache.
To monitor query cache performance, use
SHOW STATUS
to view the cache status variables:
mysql> SHOW STATUS LIKE 'Qcache%';