MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6
These views summarize file I/O, grouped by host and event type. By default, rows are sorted by host and descending total I/O latency.
The host_summary_by_file_io_type
and
x$host_summary_by_file_io_type
views have these columns:
host
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.
event_name
The file I/O event name.
total
The total number of occurrences of the file I/O event for the host.
total_latency
The total wait time of timed occurrences of the file I/O event for the host.
max_latency
The maximum single wait time of timed occurrences of the file I/O event for the host.