The file_instances Table
The file_instances table lists all the files seen by the Performance Schema when executing file I/O instrumentation. If a file on disk has never been opened, it will not be in file_instances. When a file is deleted from the disk, it is also removed from the file_instances table.
The file_instances table has these columns:
FILE_NAMEThe file name.
EVENT_NAMEThe instrument name associated with the file.
OPEN_COUNTThe count of open handles on the file. If a file was opened and then closed, it was opened 1 time, but
OPEN_COUNTwill be 0. To list all the files currently opened by the server, useWHERE OPEN_COUNT > 0.