maria-developers team mailing list archive

[Sachin Setia <sachinsetia1001@xxxxxxxxx>]

Thanks Sergei , this solved the mystery.
Regards
sachin

On Wed, Mar 23, 2016 at 12:03 AM, Sergei Golubchik <serg@xxxxxxxxxxx> wrote:

> Hi, Sachin!
>
> On Mar 22, Sachin Setia wrote:
> > 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
>
> The last key segment of every key is the row id. For dynamic row format
> it's the offset in the MYD file. For static row format (all rows have
> the same length as in your example above) it's the row number.
>
> Regards,
> Sergei
> Chief Architect MariaDB
> and security@xxxxxxxxxxx
>