Usually making a 1 ms query execute in 0.5 ms is a lot harder than making a 10 second query execute in 5 second.
One of the benefits of geometric mean is that all queries have "equal" weight in the metric, this keeps vendors from focusing on the long running queries and ignoring the short running ones.
It is one way to balance between long and short query performance.
A similar concept is applied to TPC-DS for data load, single user run (Power), multi user run (Throughput) and data maintenance (Concurrent Delete and Inserts).
One of the benefits of geometric mean is that all queries have "equal" weight in the metric, this keeps vendors from focusing on the long running queries and ignoring the short running ones. It is one way to balance between long and short query performance.
A similar concept is applied to TPC-DS for data load, single user run (Power), multi user run (Throughput) and data maintenance (Concurrent Delete and Inserts).
Check clause 7.6.3.1 in the TPC-Ds spec in http://tpc.org/tpc_documents_current_versions/pdf/tpc-ds_v3....