title: which runs first:joins or where clause
body: <p>I have a query in which i am Using 13 LEFT OUTER JOINS .The very left table has a large data,so it takes very much time to execute the query and return the result.
  But when I am using a where clause to filter the result , It takes very less time.
  Now i am confused about which executes first :the joins which produces result and then where clause filters from it OR first it filters the result the takes the join of the result.</p>