maria-developers team mailing list archive

[Nikita Malyavin <nikitamalyavin@xxxxxxxxx>]

Hi, Sergei!

On Fri, Feb 8, 2019 at 2:18 AM Sergei Golubchik <serg@xxxxxxxxxxx> wrote:

> Hi, Nikita!
>
> On Feb 08, Nikita Malyavin wrote:
> > On Tue, Feb 5, 2019 at 10:37 AM Sergei Golubchik <serg@xxxxxxxxxxx>
> wrote:
> > >
> > > as discussed, let's give the constraint the same name as the period.
> > > but don't forget to add a test where a user explicitly creates a
> > > constraint with this name. Like
> > >
> > >   create or replace table t (id int primary key, s date, e date,
> > >   period for mytime(s,e), constraint mytime (id < 100));
> >
> > Oh, I thought You meant to leave it as is. Ok, but what about making it
> > not a CHECK constraint? I mean, to make its name not overlapping with
> CHECK
> > constraints namespace. This will mean that the user can create his own
> > CHECK constraint with the same name, and have no syntax to drop PERIOD
> > constraint. What do you think about it?
>
> I thought you've wanted it a CHECK constraint. You've quoted the
> standard proving your point of view.
>
> I've also quoted that it's name shouldn't match any existing constraint
name:)
So if to choose what to violate -- I'd choose the CHECK word, so adding a
period wouldn't harm any possible existing standard-conformant table

> > > diff --git a/sql/table.h b/sql/table.h
> > > > --- a/sql/table.h
> > > > +++ b/sql/table.h
> > > > @@ -1730,6 +1747,9 @@ class IS_table_read_plan;
> > > >  /** The threshold size a blob field buffer before it is freed */
> > > >  #define MAX_TDC_BLOB_SIZE 65536
> > > >
> > > > +/** number of bytes read by uint2korr and sint2korr */
> > > > +#define korr2size 2
> > >
> > > No, that's silly. It's like #define TWO 2
> > > Of course korr2size is 2. And korr3size is 3, and korr4size is 4.
> >
> > Of course! That's the way to say "This variable was stored as a 2-byte
> > tuple".
>
> I mean, you didn't remove the magic number. It's still 2, and if you'd
> like to change it to be 3, for example, you'd still need to go and
> change the code everywhere.
>
>  Oh, so You're really thinking on such refactoring, to change the sizes of
metainfo types  rapidly? Then that 👇makes sense:
>
>   #define fieldno_size   2
>   #define fieldno_korr   uint2korr
>   #define fieldno_store  int2store
>
But I only care for self-documentation here.
Besides, maybe it then shouldn't be fixed-size, but with unicode-like
continuation marks?
AFAIK current restriction is 4k columns per table, so there should be
around four free bits. It will be even backwards compatible

> > That's why I suggested something like
> > >
> > >   #define fieldno_size   2
> > >   #define fieldno_korr   uint2korr
> > >   #define fieldno_store  int2store
> > >
> > Oh no, that'll add 9 new macros! And the number can grow...
>
> What do you mean, it's just three new macros, like above. Where's 9?
>
> 3 for fieldno, 3 for field_name_len, 3 for key_count (WITHOUT OVERLAPS
commit), and who knows -- I've also planned an flag in FOREIGN KEY support.

-- 
Yours truly,
Nikita Malyavin