The client user name. Rows for which the USER  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 . 

• ios 

The total number of file I/O events for the user. 

• io_latency 

The total wait time of timed file I/O events for the user. 

## 28.4.3.43 The user_summary_by_file_io_type and x$user_summary_by_file_io_type Views 

These views summarize file I/O, grouped by user and event type. By default, rows are sorted by user and descending total latency. 

The user_summary_by_file_io_type  and x$user_summary_by_file_io_type  views have these columns: 

• user 

The client user name. Rows for which the USER  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 user. 

• latency 

The total wait time of timed occurrences of the file I/O event for the user. 

• max_latency 

The maximum single wait time of timed occurrences of the file I/O event for the user. 

## 28.4.3.44 The user_summary_by_stages and x$user_summary_by_stages Views 

These views summarize stages, grouped by user. By default, rows are sorted by user and descending total stage latency. 

The user_summary_by_stages  and x$user_summary_by_stages  views have these columns: 

• user 

The client user name. Rows for which the USER  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 stage event name. 

• total 

