mysql> SELECT * FROM sys.host_summary_by_file_io; +------------+-------+------------+ | host | ios | io_latency | +------------+-------+------------+ | localhost | 67570 | 5.38 s | | background | 3468 | 4.18 s | +------------+-------+------------+ 

The x$host_summary_by_file_io  view summarizes the same data but displays unformatted picosecond latencies: 

mysql> SELECT * FROM sys.x$host_summary_by_file_io; +------------+-------+---------------+ | host | ios | io_latency | +------------+-------+---------------+ | localhost | 67574 | 5380678125144 | | background | 3474 | 4758696829416 | +------------+-------+---------------+ 

The view without the x$  prefix is intended to provide output that is more user friendly and easier to read. The view with the x$  prefix that displays the same values in raw form is intended more for use with other tools that perform their own processing on the data. 

Views without the x$  prefix differ from the corresponding x$  views in these ways: 

•Byte counts are formatted with size units using format_bytes() . 

•Time values are formatted with temporal units using format_time() . 

•SQL statements are truncated to a maximum display width using format_statement() . 

## 28.4.3.1 The host_summary and x$host_summary Views 

•Path name are shortened using format_path() . 

These views summarize statement activity, file I/O, and connections, grouped by host. 

The host_summary  and x$host_summary  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 . 

• statements 

The total number of statements for the host. 

• statement_latency 

The total wait time of timed statements for the host. 

• statement_avg_latency 

The average wait time per timed statement for the host. 

• table_scans 

The total number of table scans for the host. 

