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Re: Implementing implicit primary key in mysql server


Hi Sergei,

You are right, let users add primary key is best.
But I can't let users who don't want to create primary key can't use our
MySQL service.
Amazon RDS also allow users to create the tables without primary key, just
change binlog_format to MIXED to solve replication problem.

I think this feature is very useful for any MySQL cloud service providers,
all of them will face this problem in one day.
I will try to do some analysis/research in this feature implement first, I
will need your help :-)

I will notice any new updates in this email.


On Wed, Jun 19, 2013 at 5:14 PM, Sergei Golubchik <serg@xxxxxxxxxxx> wrote:

> Hi, Lixun!
> On Jun 18, Lixun Peng wrote:
> > Hi,
> >
> > As we know, InnoDB has implicit primary key if a table hasn't defined
> > a primary key.  However MySQL server doesn't know this primary key, so
> > this primary key will not apear in binlog.
> >
> > When we are using ROW format binlog for replication, if a table has no
> any
> > indexes, that's a disaster. If a table without indexes do a DML
> > (UPDATE/DELETE), of course it will run a long time in master, but in
> slave,
> > it still need a long time. It will cause serious slave replication delay.
> ...
> > I think mysql server can do the same thing as InnoDB do, if user doesn't
> > define the primary key, mysql can add the primary key automatically.
> >
> > How do you think?
> Well, that's doable. A much easier solution would be to require a user
> to create a primary key. It's a one-line change:
> -  Table_flags ha_table_flags() const { return cached_table_flags; }
> +  Table_flags ha_table_flags() const { return cached_table_flags |
> But what you suggest is possible too, I believe.
> Regards,
> Sergei

Senior Database Engineer @ Taobao.com

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