code: @Override
  	public long getObjectClass(long oid) {
  		FilePos oie = oidIndex.findOid(oid);
  		if (oie == null) {
  			throw DBLogger.newObjectNotFoundException("OID not found: " + Util.oidToString(oid));
  		}
  		
  		try {
  			fileInAP.seekPage(PAGE_TYPE.DATA, oie.getPage(), oie.getOffs());
  			return DataDeSerializerNoClass.getClassOid(fileInAP);
  		} catch (Exception e) {
  			throw DBLogger.newObjectNotFoundException(
  					"ERROR reading object: " + Util.oidToString(oid));
  		}
  	}
docs: Get the class of a given object.