When an IBMDB2I table is created, a File Level ID (FID) file is created in the database directory. This file has an extension .FID and contains the last known FID of the associated DB2 for i physical file. The IBMDB2I engine uses this FID value to determine whether incompatible changes have been made to the table by an external (non-MySQL) interface. If the physical file is altered, DB2 for i automatically generates a new FID. The next time IBMDB2I attempts to access the file, it will detect that the new FID does not match the known FID, and it will prevent MySQL from using the table.

In some cases, the changes to the physical file that cause the FID to be updated may not adversely affect access through MySQL and IBMDB2I. In this case, a user may wish to override the FID check that IBMDB2I performs. A user with appropriate permissions may do so simply by deleting the .FID file associated with the table and performing a FLUSH TABLE command against the table. IBMDB2I will then regenerate the file with the new FID the next time the table is accessed from MySQL.

If triggers or constraints are applied to the table from a native DB2 interface, they will be respected when accessing the table from MySQL, but MySQL will have no knowledge of the triggers or constraints. Likewise, views and indexes can be created over the tables from a DB2 interface, but the indexes will not be accessible from MySQL.