Repairing Indexes in Sbspaces and External Spaces
The oncheck utility can repair an index in an sbspace or external space if the index is created using an access method that supports the oncheck -y option.
Although the oncheck utility does not repair fragmented indexes, user-defined access methods can repair them. For more information about the oncheck options that access methods support, see the Informix® DataBlade® API Programmer's Guide or the Informix® Virtual-Index Interface Programmer's Guide.