mi_integer mi_id_fragid(MI_AM_ROWID_DESC *rowidDesc)

rowidDesc

points to the row-ID descriptor.

The am_insert purpose function calls mi_id_fragid() to obtain a value and add it to the index entry with the key.

The integer identifies the fragment that contains the row this key indexes.

See the description of functions mi_id_setfragid(), mi_id_rowid(), and mi_id_setrowid().