Now if only everyone's mom understood the concept of a linear set operation... :)
A good example that would also help someone appreciate the power of map/reduce might be something like "how many times does each letter of the alphabet appear in the library?" For the map step I take shelf 1 and you take shelf 2, but now for each book we'll have to write down something like "a:300,b:50,c:90,..." and so on. But now there are more things to "reduce" than there are books (since we now have a value for the number of occurrences of each letter in the alphabet for every book). Well, there's nothing stopping us from splitting up the reduce step as well - we could split it up by shelf again (where you add the totals for each letter on your shelf and I'll do mine, then we'll do one final reduce of at the end), or you can add up letters a-m and I'll do n-z.
A good example that would also help someone appreciate the power of map/reduce might be something like "how many times does each letter of the alphabet appear in the library?" For the map step I take shelf 1 and you take shelf 2, but now for each book we'll have to write down something like "a:300,b:50,c:90,..." and so on. But now there are more things to "reduce" than there are books (since we now have a value for the number of occurrences of each letter in the alphabet for every book). Well, there's nothing stopping us from splitting up the reduce step as well - we could split it up by shelf again (where you add the totals for each letter on your shelf and I'll do mine, then we'll do one final reduce of at the end), or you can add up letters a-m and I'll do n-z.