maria-developers team mailing list archive

[Sergei Golubchik <serg@xxxxxxxxxxx>]

Hi, Shubham!

On Mar 03, Shubham Barai wrote:
> 
> I am interested in the project "Unique indexes for blobs".I have read the
> description of the project given on the link
> https://jira.mariadb.org/browse/MDEV-371.

Great!

> I want to know what exactly is the task for this project.Any help
> would be greatly appreciated

See storage/myisam/mi_create.c. You see that a myisam table can have
keys (defined in MI_KEYDEF structure) and so-called "uniques" (defined
by MI_UNIQUEDEF).

Keys have length limitation, keys can be unique (HA_NOSAME flag) or not
unique.

"uniques" have no length limitation.

When one creates a unique key from SQL:

  CREATE TABLE ... (... UNIQUE KEY (...) ... )

this will always create a key (MI_KEYDEF) in a MyISAM table. That's why
unique constraints in MyISAM have a limited length.

This task is about creating MI_UNIQUEDEF "uniques" instead of MI_KEYDEF
"keys" for long unique constraints.

Regards,
Sergei
Chief Architect MariaDB
and security@xxxxxxxxxxx