sys Schema Views The host from which the client connected. Rows for which the  HOST  column in the underlying Performance Schema table is  NULL  are assumed to be for background threads and are reported with a host name of  background . The file I/O event name. The total number of occurrences of the file I/O event for the host. The total wait time of timed occurrences of the file I/O event for the host. The maximum single wait time of timed occurrences of the file I/O event for the host. 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$host_summary_by_stages  views have these columns: The host from which the client connected. Rows for which the  HOST  column in the underlying Performance Schema table is  NULL  are assumed to be for background threads and are reported with a host name of  background . The stage event name. The total number of occurrences of the stage event for the host. The total wait time of timed occurrences of the stage event for the host. The average wait time per timed occurrence of the stage event for the host. These views summarize overall statement statistics, grouped by host. By default, rows are sorted by descending total latency. The  host_summary_by_statement_latency  and  x$host_summary_by_statement_latency views have these columns: 28.4.3.5 The host_summary_by_statement_latency and x $host_summary_by_statement_latency Views 5143 28.4.3.4 The host_summary_by_stages and x$host_summary_by_stages Views • event_name • total • total_latency • max_latency • host • event_name • total • total_latency • avg_latency