MS SQL Server Joins Question:

Merge join If both join relations come in order, sorted by the join attribute(s), the system can perform the join trivially, thus: It can consider the current group of tuples from the inner relation which consists of a set of contiguous tuples in the inner relation with the same value in the join attribute. For each matching tuple in the current inner group, add a tuple to the join result. Once the inner group has been exhausted, advance both the inner and outer scans to the next group.