File I/O Summary Tables

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_instance: File events summarized per file instance

For example:

mysql> SELECT * FROM file_summary_by_event_name\G
...
*************************** 2. row ***************************
 EVENT_NAME: wait/io/file/sql/binlog
 COUNT_STAR: 31
 SUM_TIMER_WAIT: 8243784888
 MIN_TIMER_WAIT: 0
 AVG_TIMER_WAIT: 265928484
 MAX_TIMER_WAIT: 6490658832
...
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
 EVENT_NAME: wait/io/file/sql/ERRMSG
 OBJECT_INSTANCE_BEGIN: 4686193384
 COUNT_STAR: 5
 SUM_TIMER_WAIT: 13990154448
 MIN_TIMER_WAIT: 26349624
 AVG_TIMER_WAIT: 2798030607
 MAX_TIMER_WAIT: 8150662536
...

TRUNCATE TABLE is permitted for summary tables. It resets the counters to zero rather than removing rows.

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.
file_summary_by_instance has FILE_NAME, EVENT_NAME, and (as of MariaDB 5.6.4) OBJECT_INSTANCE_BEGIN columns. Each row summarizes events for a given file instrument instance.

The file I/O summary tables have the following summary columns containing aggregated values. (Before MariaDB 5.6.4, the tables contain only the Only COUNT_READ COUNT_WRITE SUM_NUMBER_OF_BYTES_READ, and SUM_NUMBER_OF_BYTES_WRITE aggregation columns.) Some columns are more general and have values that are the same as the sum of the values of more fine-grained columns. In this way, aggregations at higher levels are available directly without the need for user-defined views that sum lower-level columns.

COUNT_STAR, SUM_TIMER_WAIT, MIN_TIMER_WAIT, AVG_TIMER_WAIT, MAX_TIMER_WAIT
These columns aggregate all I/O operations.
COUNT_READ, SUM_TIMER_READ, MIN_TIMER_READ, AVG_TIMER_READ, MAX_TIMER_READ, SUM_NUMBER_OF_BYTES_READ
These columns aggregate all read operations, including FGETS, FGETC, FREAD, and READ.
COUNT_WRITE, SUM_TIMER_WRITE, MIN_TIMER_WRITE, AVG_TIMER_WRITE, MAX_TIMER_WRITE, SUM_NUMBER_OF_BYTES_WRITE
These columns aggregate all write operations, including FPUTS, FPUTC, FPRINTF, VFPRINTF, FWRITE, and PWRITE.
COUNT_MISC, SUM_TIMER_MISC, MIN_TIMER_MISC, AVG_TIMER_MISC, MAX_TIMER_MISC
These columns aggregate all other I/O operations, including CREATE, DELETE, OPEN, CLOSE, STREAM_OPEN, STREAM_CLOSE, SEEK, TELL, FLUSH, STAT, FSTAT, CHSIZE, RENAME, and SYNC. There are no byte counts for these operations.

File I/O Summary Tables

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