Both GDBM and Linux support large files (in excess of 2 GB), but that support has to be compiled into the binary. Either GDBM or Linux has NOT been compiled for Maemo with large file support. One alternative (which is obviously not ideal) is to split your database into two separate files, e.g. one for the United States, one for Europe, etc. A programmatic solution would be for Maemo Mapper to start splitting database files itself based on heuristics, but that complicates the implementation (potentially requiring Maemo Mapper to search multiple databases per tile access). I will have to investigate further....