oracle event 'disk file operations i/o'

Disk file operations I/O This event is used to wait for disk file operations (for example, open, close, seek, and resize). It is also used for miscellaneous I/O operations such as block dumps and password file accesses.

Wait Time: The wait time is the actual time it takes to do the I/O Parameter Description FileOperation Type of file operation fileno File identification number filetype Type of file (for example, log file, data file, and so on)

today, the event 'disk file operations i/o' cost 0.45s, so i pay attention to it.

if we look into 10046 trace file.it show as follow: __________________________________________________________________________________________________

WAIT #406867792: nam='Disk file operations I/O' ela= 244361 FileOperation=2 fileno=4 filetype=2 obj#=485041 tim=469151246210

.....

WAIT #406867792: nam='Disk file operations I/O' ela= 91489 FileOperation=2 fileno=5 filetype=2 obj#=485683 tim=469151708966

WAIT #406867792: nam='db file scattered read' ela= 5876 file#=5 block#=609704 blocks=8 obj#=485683 tim=469151714974

WAIT #406867792: nam='Disk file operations I/O' ela= 54923 FileOperation=2 fileno=7 filetype=2 obj#=485683 tim=469151770139 ..... __________________________________________________________________________________________________

select * from DBA_DATA_FILES where file_id in (4,5,7); see whick file

select * from dba_objects where object_id IN (485683,485041); see which object

after check, it seems mean creating i/o handle for oracle reading specifically file.