GFE Server-Timing header has recently been enabled in all Cloud Spanner APIs. That means Spanner users can now retrieve the latency metric on GFE for every Cloud Spanner response. It can help to better distinguish the source of latency between client, networking, GFE and Spanner backend.


  • Today Cloud customers can see the latency metrics and tracing spans of client RPCs by using OpenCensus in the client libraries. (See OpenCensus guide.)
  • Latency on Spanner requests is automatically captured and exposed as a Stackdriver system metric “spanner.googleapis.com/api/request_latencies”.
  • In addition, Spanner QueryStats are available in the responses if QueryMode is set to Profile

Yang Song

Software Engineer at Google

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