twitter/zipkin — pull request #397 by synk (2014-07-06 08:11:09+00:00)
Title: Fix sql of AnormIndex.getTracesDuration to get right duration.

If I understand correctly, `Index.getTracesDuration` should return the duration of the entire trace. But current implementation of `AnormIndex.getTracesDuration` returns a span's duration rather than a trace's one. Because of this, `QueryService` can't sort correctly by duration.