# Performance Schema file\_summary\_by\_instance Table
The [Performance Schema](/docs/server/reference/system-tables/performance-schema.md) `file_summary_by_instance` table contains file events summarized by instance. It contains the following columns:
| Column | Description |
| ----------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| FILE\_NAME | File name. |
| EVENT\_NAME | Event name. |
| OBJECT\_INSTANCE\_BEGIN | Address in memory. Together with FILE\_NAME and EVENT\_NAME uniquely identifies a row. |
| COUNT\_STAR | Number of summarized events |
| SUM\_TIMER\_WAIT | Total wait time of the summarized events that are timed. |
| MIN\_TIMER\_WAIT | Minimum wait time of the summarized events that are timed. |
| AVG\_TIMER\_WAIT | Average wait time of the summarized events that are timed. |
| MAX\_TIMER\_WAIT | Maximum wait time of the summarized events that are timed. |
| COUNT\_READ | Number of all read operations, including FGETS, FGETC, FREAD, and READ. |
| SUM\_TIMER\_READ | Total wait time of all read operations that are timed. |
| MIN\_TIMER\_READ | Minimum wait time of all read operations that are timed. |
| AVG\_TIMER\_READ | Average wait time of all read operations that are timed. |
| MAX\_TIMER\_READ | Maximum wait time of all read operations that are timed. |
| SUM\_NUMBER\_OF\_BYTES\_READ | Bytes read by read operations. |
| COUNT\_WRITE | Number of all write operations, including FPUTS, FPUTC, FPRINTF, VFPRINTF, FWRITE, and PWRITE. |
| SUM\_TIMER\_WRITE | Total wait time of all write operations that are timed. |
| MIN\_TIMER\_WRITE | Minimum wait time of all write operations that are timed. |
| AVG\_TIMER\_WRITE | Average wait time of all write operations that are timed. |
| MAX\_TIMER\_WRITE | Maximum wait time of all write operations that are timed. |
| SUM\_NUMBER\_OF\_BYTES\_WRITE | Bytes written by write operations. |
| COUNT\_MISC | Number of all miscellaneous operations not counted above, including CREATE, DELETE, OPEN, CLOSE, STREAM\_OPEN, STREAM\_CLOSE, SEEK, TELL, FLUSH, STAT, FSTAT, CHSIZE, RENAME, and SYNC. |
| SUM\_TIMER\_MISC | Total wait time of all miscellaneous operations that are timed. |
| MIN\_TIMER\_MISC | Minimum wait time of all miscellaneous operations that are timed. |
| AVG\_TIMER\_MISC | Average wait time of all miscellaneous operations that are timed. |
| MAX\_TIMER\_MISC | Maximum wait time of all miscellaneous operations that are timed. |
I/O operations can be avoided by caching, in which case they will not be recorded in this table.
You can [TRUNCATE](/docs/server/reference/sql-statements/table-statements/truncate-table.md) the table, which will reset all counters to zero.
## Example
```sql
SELECT * FROM file_summary_by_instance\G
...
*************************** 204. row ***************************
FILE_NAME: /var/lib/mysql/test/db.opt
EVENT_NAME: wait/io/file/sql/dbopt
OBJECT_INSTANCE_BEGIN: 140578961971264
COUNT_STAR: 6
SUM_TIMER_WAIT: 39902495024
MIN_TIMER_WAIT: 177888
AVG_TIMER_WAIT: 6650415692
MAX_TIMER_WAIT: 21026400404
COUNT_READ: 1
SUM_TIMER_READ: 21026400404
MIN_TIMER_READ: 21026400404
AVG_TIMER_READ: 21026400404
MAX_TIMER_READ: 21026400404
SUM_NUMBER_OF_BYTES_READ: 65
COUNT_WRITE: 0
SUM_TIMER_WRITE: 0
MIN_TIMER_WRITE: 0
AVG_TIMER_WRITE: 0
MAX_TIMER_WRITE: 0
SUM_NUMBER_OF_BYTES_WRITE: 0
COUNT_MISC: 5
SUM_TIMER_MISC: 18876094620
MIN_TIMER_MISC: 177888
AVG_TIMER_MISC: 3775218924
MAX_TIMER_MISC: 18864558060
*************************** 205. row ***************************
FILE_NAME: /var/log/mysql/mariadb-bin.000157
EVENT_NAME: wait/io/file/sql/binlog
OBJECT_INSTANCE_BEGIN: 140578961971968
COUNT_STAR: 6
SUM_TIMER_WAIT: 73985877680
MIN_TIMER_WAIT: 251136
AVG_TIMER_WAIT: 12330979468
MAX_TIMER_WAIT: 73846656340
COUNT_READ: 0
SUM_TIMER_READ: 0
MIN_TIMER_READ: 0
AVG_TIMER_READ: 0
MAX_TIMER_READ: 0
SUM_NUMBER_OF_BYTES_READ: 0
COUNT_WRITE: 2
SUM_TIMER_WRITE: 62583004
MIN_TIMER_WRITE: 27630192
AVG_TIMER_WRITE: 31291284
MAX_TIMER_WRITE: 34952812
SUM_NUMBER_OF_BYTES_WRITE: 369
COUNT_MISC: 4
SUM_TIMER_MISC: 73923294676
MIN_TIMER_MISC: 251136
AVG_TIMER_MISC: 18480823560
MAX_TIMER_MISC: 73846656340
```
*This page is licensed: CC BY-SA / Gnu FDL*
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