Have you used pt-online-schema-change.html from
http://www.percona.com/doc/percona-toolkit/2.0/pt-online-schema-change.html ?
What do you think about this tool?

Best regards,
Rafal Radecki.


2013/7/8 Rafa? Radecki <radecki.rafal@gmail.com>

> Hi All.
>
> I would like to change the layout of my production database, I would like
> to add a column to an existing table. As I think before the ALTER TABLE
> statement all access to the database should be denied/ended, then the ALTER
> TABLE should be performed, and then user/applications should be able to use
> the database once again.
>
> My tables is quite small ~4MB data & indexes.
>
> So is the ALTER TABLE on a running/opened to clients database/table
> desirable or should it be run when all access to the database/table is
> forbidden?
>
> Best regards,
> Rafal Radecki.
>