int (long offset) { // recordId=0 is used as NULL_ID (i.e. invalid) id, hence '+1' for the 1st record to have {id:1} long longId = (offset - recordsStartOffset()) / OFFSET_BUCKET + 1; int id = (int)longId; assert longId == id : "offset " + offset + " is out of Integer bounds"; assert id > 0 : "id " + id + " is not a valid id"; return id; }