code: public static int recordSize(Schema sch) {
  		int pos = 0;
  		for (String fldname : sch.fields())
  			pos += Page.maxSize(sch.type(fldname));
  		return pos < MIN_REC_SIZE ? MIN_REC_SIZE : pos;
  	}
docs: Returns the number of bytes required to store a record with the specified
  schema in disk.
  
  @param sch
  the table's schema
  @return the size of a record, in bytes