What is the “query per hour” rating (QphD)?
The query per hour rating is equal to the geometric mean (i.e., square root of the product) of the power and throughput metrics. Its primary purpose is to derive a single performance rating that can be used to compute price-performance. As a result of combining the power metric (which due to its use of a geometric mean is sensitive to short queries) and the throughput metric (which due to its implicit use of the arithmetic mean is sensitive to long running queries) QphD places attention on both the ability to make simple queries run very fast, as well as on the ability to make the very long queries run faster. The use of either metric alone would place to much emphasis on either short or long-running queries.
