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The file I/O summary tables aggregate information about I/O operations:
file_summary_by_event_name: File events summarized per event name
file_summary_by_event_name
file_summary_by_instance: File events summarized per file instance
file_summary_by_instance
For example:
mysql> SELECT * FROM file_summary_by_instance\G ... *************************** 2. row *************************** FILE_NAME: /var/mysql/share/english/errmsg.sys EVENT_NAME: wait/io/file/sql/ERRMSG COUNT_READ: 3 COUNT_WRITE: 0 SUM_NUMBER_OF_BYTES_READ: 42211 SUM_NUMBER_OF_BYTES_WRITE: 0 ... *************************** 6. row *************************** FILE_NAME: /var/mysql/data/binlog.000001 EVENT_NAME: wait/io/file/sql/binlog COUNT_READ: 0 COUNT_WRITE: 0 SUM_NUMBER_OF_BYTES_READ: 0 SUM_NUMBER_OF_BYTES_WRITE: 0 ...
SELECT * FROM file_summary_by_instance\G
TRUNCATE TABLE is permitted for summary tables. It resets the counters to zero rather than removing rows.
TRUNCATE TABLE
The file I/O summary tables have these grouping columns to indicate how events are aggregated:
file_summary_by_event_name has an EVENT_NAME column. Each row summarizes events for a given instrument.
EVENT_NAME
file_summary_by_instance has FILE_NAME and EVENT_NAME columns. Each row summarizes events for a given file instrument instance.
FILE_NAME
The file I/O summary tables have these summary columns containing aggregated values:
COUNT_READ
The number of read operations in the summarized events.
COUNT_WRITE
The number of write operations in the summarized events.
SUM_NUMBER_OF_BYTES_READ
The number of bytes read in the summarized events.
SUM_NUMBER_OF_BYTES_WRITE
The number of bytes written in the summarized events.
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