Hi Sergei!

On Tue, Sep 22, 2020 at 8:31 PM Sergei Golubchik <serg@mariadb.org> wrote:
Hi, Aleksey!

Wow, this comes so late, sorry! :(

But it's fixVersion=10.6 and on the top my list, so here you are.

On May 07, Aleksey Midenkov wrote:
> >
> > The conclusion, I believe, is that system_versioning_modify_history
> > should allow INSERTs when secure_timestamp=NO, and it should allow
> > UPDATE/DELETE only for a SUPER user when secure_timestamp=NO or SUPER.
> I don't see a reason to argue on that. The only thing that is not
> clear, why we don't allow INSERTs when secure_timestamp=SUPER?

Sure, I meant back then that INSERT/UPDATE/DELETE would be allowed when

But now I think we shouldn't really allow UPDATE/DELETE at all.

I wrote earlier that "Now, with a SUPER privilege and
secure_timestamp=NO or SUPER, one can use the BINLOG command and truly
edit the history arbitrarily, by faking row events."

Which is true, but we want to change it.
In https://jira.mariadb.org/browse/MDEV-18432.

So, it's looks reasonable to allow only INSERTs - they can fake new
history, which is needed for mysqldump, but at least there will be no
command to selectively delete or modify history.

> > The second thing I don't like at all, is when a table is created like
> >
> >
> > with row_start/row_end implicit. You don't have it in the test, but
> > anyway one should be able to load history into such a table, while
> > the table does not have row_start and row_end columns. From the user
> > point of view these columns don't exist, they're pseudo-columns,
> > like ROWID. They just cannot be insertable-into, conceptually. But a
> > user will want to restore the history, right? I don't have a
> > solution for this yet :( Any ideas?
> We don't have to follow the conception if it doesn't help us. Since we
> have physical row_start/row_end, we don't have to pretend they don't
> exist. Who will win from that?

Yes, you're right.

Then for the purpose of mysqldump they should be insertable-into. And
mysqldump should only care to list them explicitly in the column list,
like with any other insivible columns. This looks easy.

And mysqldump should take care of setting system_versioning_insert_history sysvar. Right? Is everything else in the task description OK?

1. Add server variable system_versioning_insert_history which will allow INSERT history rows.
2. If secure_timestamp is YES or REPLICATION, system_versioning_insert_history does not have effect. If secure_timestamp is SUPER, system_versioning_insert_history requires special privilege (same as for setting current timestamp).

VP of MariaDB Server Engineering
and security@mariadb.org

All the best,

Aleksey Midenkov