These views summarize statement stages, grouped by host. By default, rows are sorted by host and descending total latency.
          The host_summary_by_stages and
          x$host_summary_by_stages views
          have these columns:
- host- The host from which the client connected. Rows for which the - HOSTcolumn in the underlying Performance Schema table is- NULLare assumed to be for background threads and are reported with a host name of- background.
- event_name- The stage event name. 
- total- The total number of occurrences of the stage event for the host. 
- total_latency- The total wait time of timed occurrences of the stage event for the host. 
- avg_latency- The average wait time per timed occurrence of the stage event for the host.