The article discusses how new computer systems called relational database machines can be tested to see how well they work. The researchers created test programs to measure the performance of join operations, which are an important part of databases. Join operations involve combining data from different parts of a database. By running tests with different conditions like data size and how data is stored, they could see how well the machines handled these operations. The researchers tested different types of joins to see how the machines compared. They used this information to analyze which machines performed the best when it came to joining data together.