Pair: total work-based optimizer
- Construct a query plan containing only a single join using two unblocked relations.
- Analyzes each pair of unblocked relations sharing a join predicate.
- Chooses the join with the least total cost to execute.
- Materialize the results of the join to disk.
- Avoids Cartesian products, joins whose produced results take longer to read from disk than to compute from scratch.