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Re: dc2ace70f1b: Syntax with MIGRATE keyword

 

Sergei,

On Wed, Sep 1, 2021 at 10:13 PM Sergei Golubchik <serg@xxxxxxxxxxx> wrote:
>
> Hi, Aleksey!
>
> On Sep 01, Aleksey Midenkov wrote:
> > > >
> > > > +move_out_partition:
> > > > +        MIGRATE_SYM PARTITION_SYM
> > > > +        | MIGRATE_SYM OUT_SYM PARTITION_SYM
> > >
> > > Where does this OUT_SYM came out from?
> > > It doesn't add any values, it doesn't make the syntax more natural.
> > > Why did you add it?
> >
> > I think that helps to make syntax more natural if we do MIGRATE
> > PARTITION in both directions.
> > If it is written MIGRATE OUT or MIGRATE IN that is easier to
> > understand what's going on. FROM/TO in the end is not helping much
> > because it is harder to notice. Partition specification presence or
> > absence: not so explicit to understand quickly.
>
> It incorrect English. And it's a noise word that adds no value and
> doesn't make anything easier to understand.
>
>   MIGRATE PARTITION x TO TABLE y
>
> is correct and unambigous although not a very traditional use of the
> word "migrate". MIGRATE OUT PARTITION x TO TABLE y is just wrong.
>

If there is "move in" and "move out", "migrate in" and "migrate out"
cannot be wrong. Look for examples for "migrate out to" and "migrate
in from".

> > > > +        ;
> > > > +
> > > > +to_table:
> > > > +        TO_SYM TABLE_SYM
> > > > +        | TO_SYM
> > >
> > > Let's keep the TABLE_SYM. Saying
> > >
> > >    MIGRATE PARTITION p1 TO p2
> > >
> > > is very vague, the syntax should explicitly say that it migrates a
> > > PARTITION to a TABLE. The statement mentions many different types of
> > > objects, if should be clear about what object type every identifier
> > > refers to.
> >
> > That is a shortcut for easier typing and that is precious for
> > command-line work! If some names can make misunderstanding one can
> > always write
> >
> > MIGRATE PARTITION p1 TO TABLE p2
> >
> > Please do not restrict user freedom to choose between verbosity and
> > brevity. I guess you have a preference for perl over python (and the
> > democracy over dictatorship).
>
> I do. But it's SQL, not perl. SQL is very verbose even when it isn't
> really justified. And here is is justified, so let's keep the syntax
> unambigous.

And why this is good and should be followed? There are shortcuts in SQL too.
Okay, let's keep this unambiguous for a while.

>
> Regards,
> Sergei
> VP of MariaDB Server Engineering
> and security@xxxxxxxxxxx



-- 
All the best,

Aleksey Midenkov
@midenok


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