You have a large dataset of key-value pairs, where the keys are strings, and the values are
integers. For each unique key, you want to identify the largest integer. In writing a MapReduce
program to accomplish this, can you take advantage of a combiner?
No, a combiner would not be useful in this case.
Yes, but the number of unique keys must be known in advance.
Yes, as long as all the keys fit into memory on each node.
Yes, as long as all the integer values that share the same key fit into memory on each node.