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Re: [External] Binlog handling of faulty DDL query
Reindl Harald <h.reindl@xxxxxxxxxxxxx>
Sun, 2 Sep 2018 23:17:47 +0200
the lounge interactive design
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Am 02.09.18 um 23:04 schrieb Pavel Ivanov:
> Note that to make CREATE USER atomic mysql.user table will need to be
> made to use InnoDB storage engine rather than MyISAM. And that would
> involve pretty significant amount of changes throughout the code base.
> And yes, MySQL switched mysql.user table (as well as other mysql.*
> tables) to use InnoDB storage engine only in 8.0. In 5.7 and earlier
> it was still MyISAM.
accept or refuse the whole query and so log it complete or not at all is
a different beast then make it atomic
please don't consider make InnoDB mandatory, here are small
mariadb-servers where only loading innodb would multiply the whole footprint
> On Sun, Sep 2, 2018 at 5:59 AM Simon Mudd <simon.mudd@xxxxxxxxxxx> wrote:
>> On 2 Sep 2018, at 11:27, Sachin Setiya <sachin.setiya@xxxxxxxxxxx> wrote:
>> Hi Everyone!
>> Suppose this case
>> CREATE USER
>> user1@localhost IDENTIFIED BY 'BsG9#9.cem#!85',
>> user2@localhost IDENTIFIED BY 'x';
>> user2 has too short passowrd which will give error (if we use security plugin)
>> IN the case of *mariadb* we will create user1 and wont create user2
>> In the case of *mysql (8.0)* we will return error and we will not
>> create any user
>> Our approach create a lots of problem for binary log and
>> replication(MDEV-14716, MDEV-16728)
>> Because in Query_log_event::write() we write the whole query not the
>> parts of it.
>> So we have 2 options to solve this either write modified query into
>> binlog or do what mysql does.
>> So what you think , which approach we should use ? Or there is another
>> better way ?
>> I’m a user of MySQL / MariaDB and I hadn’t been aware you can use CREATE USER on more than one user. I guess I need to study the manual more …
>> Having said that you mention MySQL 8.0 and say the behaviour there is atomic. Is it also atomic in 5.7 and earlier? It would be good to know.
>> [ I then go to check …]
>> Also do we want the statement to be atomic? I don’t know if this comes under SQL specifications or not. If it does follow that.
>> If not as a user that administers mysql account information I’d prefer the statement to be atomic. As you say it causes less confusion
>> and it either works or does not. That’s easier to handle when you automatic account creation and maintenance which some of us do.
>> So looking at https://dev.mysql.com/doc/refman/8.0/en/create-user.html it seems the atomic part is explicitly mentioned.
>> https://dev.mysql.com/doc/refman/5.7/en/create-user.html does not give this guarantee so behaviour more likely roughly matches current MariaDB behaviour.
>> In any account management I’ve used I’ve always handled users one by one and thus atomic behaviour is implicitly guaranteed.
>> However, given it is possible to create more than one user at once I’d certainly prefer to see the behaviour being atomic as otherwise you’re going to be
>> forced to check each of the accounts on the server after attempting to create them to see if they are there and configured as you expect. That
>> task is more complex than handing a more simple error.
>> While this seems to be a dirty word now I would like to see as much compatibility in MariaDB vs [Oracle] MySQL as possible and where this is reasonable.
>> Behaviour in MySQL has changed and while it doesn’t have to change in MariaDB the change in MySQL seems “reasonable”. I think it would be good
>> for MariaDB to follow that for the reasons stated above, if possible.
>> Based on expected behaviour what gets written to the binlog I think becomes easier. You send the statement as given as you only send it if it has succeeded.