maria-discuss team mailing list archive

[Peter Laursen <peter_laursen@xxxxxxxxxx>]

I personally think like this


     col1 JSON

being equal to

     col1 LONGTEXT CHARACTER SET utf8mb4 CHECK(JSON_VALID(col1))


.. would be nice.


-- Peter

On Thu, Jul 13, 2017 at 12:03 PM, Sergei Golubchik <serg@xxxxxxxxxxx> wrote:

> Hi, Peter!
>
> On Jul 13, Peter Laursen wrote:
> >  -- MariaDB 10.2.7
> > CREATE TABLE `jsontst`( `id` INT NOT NULL AUTO_INCREMENT, `str` JSON,
> > PRIMARY KEY (`id`) ) ENGINE=Aria CHARSET=latin1;
> > SHOW CREATE TABLE `jsontst`;
> > /* returns
> > CREATE TABLE `jsontst2` (
> >   `id` int(11) NOT NULL AUTO_INCREMENT,
> >   `str` text DEFAULT NULL,
> >   PRIMARY KEY (`id`)
> > ) ENGINE=Aria DEFAULT CHARSET=latin1 PAGE_CHECKSUM=1
> > */
> >
> > readings:
> > https://jira.mariadb.org/browse/MDEV-9144
> > https://bugs.mysql.com/bug.php?id=86875
> >
> > As you see except for JSON in MariaDB just being a synonym of TEXT there
> > are two more significant differences
> > 1) length: in MySQL JSON has the lenght of a LONGTEXT - in MariaDB it is
> a
> > (plain) TEXT
> > 2) encoding: in MySQL the utf8mb4 character set is enforced for JSON
> data -
> > in MariaDB you may specify any character set.
> >
> > I think in particular 2nd point could cause problems (unicode
> > garbling) when loading a dump with JSON data from MySQL. Basically
> > because latin1 is still default character set in MariaDB.
> >
> > Are you aware of the 2 differences? I think the major reason for
> > introducing JSON in MariaDB is compability concerns with MySQL.  But
> > the 2 points here are IMO incompabilites that could have been avoided?
>
> JSON functions were added for SQL Standard and for MySQL compatibility.
>
> But JSON alias for TEXT - it was only for MySQL compatibility, no other
> reasons. So you're right, these issues should be fixed.
>
> 1. LONGTEXT - no questions here, we'll fix it.
>
> 2. charset. If one would write
>
>      col1 JSON CHARACTER SET latin1
>
> That'll be an error, right?
>
> 3. I could make JSON to imply validity checks too.
>
>      col1 JSON
>
> being equal to
>
>      col1 LONGTEXT CHARACTER SET utf8mb4 CHECK(JSON_VALID(col1))
>
> is it what users would expect for compatibility reasons?
>
> Regards,
> Sergei
> Chief Architect MariaDB
> and security@xxxxxxxxxxx
>