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 is not 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_COUNTis 0. To list all the files currently opened by the server, useWHERE OPEN_COUNT > 0.
          TRUNCATE TABLE is not permitted
          for the file_instances table.