title: MySQL drop foreign key too slow?
body: <p>Dropping a foreign key on a table with 215k+ (with alter table) records seems to take a long time (17+ minutes). Is it possible to somehow speed up the process? 
  SQL: ALTER TABLE <code>sales_flat_order_grid</code> DROP FOREIGN KEY <code>FK_SALES_FLAT_ORDER_GRID_STORE</code>;</p>
  
  <p>It is a magento upgrade that takes ages</p>