In ORDER BY MySQL seems to set the key read flag also in the case where the primary key contains only a prefix of a column - not the whole column; to prevent potential bugs retrieve the whole column if the index contains a prefix of it


sql/ha_innodb.cc:
  In ORDER BY MySQL seems to set the key read flag also in the case where the primary key contains only a prefix of a column - not the whole column; to prevent potential bugs retrieve the whole column if the index contains a prefix of it
innobase/dict/dict0dict.c:
  In ORDER BY MySQL seems to set the key read flag also in the case where the primary key contains only a prefix of a column - not the whole column; to prevent potential bugs retrieve the whole column if the index contains a prefix of it
innobase/include/dict0dict.h:
  In ORDER BY MySQL seems to set the key read flag also in the case where the primary key contains only a prefix of a column - not the whole column; to prevent potential bugs retrieve the whole column if the index contains a prefix of it