Physical file

1, the system file table space ibdata1
2, the temporary files tablespace ibtmp1
. 3, the redo tablespace files ib_logfile0, ib_logfile1, ib_logfile2
. 4, Use the undo tablespace files undo001, undo002, undo003
. 5, the user file table space xxx.ibd, the user table space, As the name suggests, it is a user-created table space,
   if open a separate table space parameters, then a table space will correspond to a physical file on disk.