Performance Schema file_instances Table
Description
The file_instances table lists instances of instruments seen by the Performance Schema when executing file I/O instrumentation, and the associated files. Only files that have been opened, and that have not been deleted, will be listed in the table.
The performance_schema_max_file_instances system variable specifies the maximum number of instrumented file objects.
| Column | Description |
|---|---|
FILE_NAME | File name. |
EVENT_NAME | Instrument name associated with the file. |
OPEN_COUNT | Open handles on the file. A value of greater than zero means that the file is currently open. |
Example
SELECT * FROM performance_schema.file_instances WHERE OPEN_COUNT>0; +----------------------------------------------------+--------------------------------------+------------+ | FILE_NAME | EVENT_NAME | OPEN_COUNT | +----------------------------------------------------+--------------------------------------+------------+ | /var/log/mysql/mariadb-bin.index | wait/io/file/sql/binlog_index | 1 | | /var/lib/mysql/ibdata1 | wait/io/file/innodb/innodb_data_file | 2 | | /var/lib/mysql/ib_logfile0 | wait/io/file/innodb/innodb_log_file | 2 | | /var/lib/mysql/ib_logfile1 | wait/io/file/innodb/innodb_log_file | 2 | | /var/lib/mysql/mysql/gtid_slave_pos.ibd | wait/io/file/innodb/innodb_data_file | 3 | | /var/lib/mysql/mysql/innodb_index_stats.ibd | wait/io/file/innodb/innodb_data_file | 3 | | /var/lib/mysql/mysql/innodb_table_stats.ibd | wait/io/file/innodb/innodb_data_file | 3 | ...
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