maria-developers team mailing list archive

[Sergei Golubchik <serg@xxxxxxxxxxx>]

Hi, Sachin!

On Jul 14, Sachin Setia wrote:
> Hello Sergei
> Actually i have one doubt  there is two options
> 1 add is_hash flag to field
> 2 add ha_unique_hash flag to field ,but i think all 16 bits of key flag is used
> so to do this i need to add another ex_flag variable in key struct and
> store it and retrieve it from frm
> currently i have done both ,but as you pointed out in review that  it
> is better to have it in key only but
> my question is that, whether is this approach is right ?

>From the storage point of view, it's much easier to put a special flag
on the field. You can store it in EXTRA2 or you can store it in the
Field::unireg_check enum.

And then you recognize your HA_UNIQUE_HASH keys by having is_hash
property on the field of the first keypart. You can even set the
HA_UNIQUE_HASH flag in the key, if HA_UNIQUE_HASH=65536, for example.
That is, it won't be stored in the frm, and you set the flag in
init_from_binary_frm_image - the flag can be used to simplify run-time
checks, but it won't be stored on disk.

Regards,
Sergei
Chief Architect MariaDB
and security@xxxxxxxxxxx