Cache consistency when using memcached and a rdbms like MySQL

Question

I have taken a database class this semester and we are studying about maintaining cache consistency between the RDBMS and a cache server such as memcached. The consistency issue

Answer 1

When you read, the following happens:

if(Key is not in cache){
  fetch data from db
  put(key,value);
}else{
  return get(key)
}

When you write, the following happens:

1 delete/update data from db
2 clear cache