Hello Devlopers 

I was debugging the source code of mariadb. My query was

MariaDB [sachin]> create table pro2(abc int primary key,xyz int , 

ass int ,unique(xyz,ass))engine=myisam;

In table2myisam function of file ha_myisam.cc i found that 

we are allocating more memory for keysegments

if (!(my_multi_malloc(MYF(MY_WME),

          recinfo_out, (share->fields * 2 + 2) * sizeof(MI_COLUMNDEF),

          keydef_out, share->keys * sizeof(MI_KEYDEF),

          &keyseg,

          (share->key_parts + share->keys) * sizeof(HA_KEYSEG),

                                               ^ here why this 

          NullS)))

    And we donot use these extra key segments because 

    suceeding for loop use only total number of share->key_parts 

    keysegments. And same in ha_maria file.Is this a bug or I am missing something 

    Regards 

    sachin