Searching for the performance bottleneck in an execution trace is an error prone and time consuming activity. Existing tools oer some comfort by providing a visual representation of trace for analysis. In this paper we present the Stethoscope, an interactive visual tool to inspect and analyze columnar database query performance, both online and online. It's unique interactive animated interface capitalizes
the large dataflow graph representation of a query execution plan, augmented with query execution trace information. We demonstrate features of Stethoscope for both online and online analysis of long running queries. It helps in understanding where time goes, how optimizers perform, and how
parallel processing on multi-core systems is exploited
