maria-developers team mailing list archive

[Alexander Barkov <bar@xxxxxxxxxxx>]

On 10/12/21 8:46 PM, Sergei Golubchik wrote:
> Hi, Alexander!
>
> On Oct 12, Alexander Barkov wrote:
> > > > diff --git a/sql/field.cc b/sql/field.cc
> > > > index 46a3a1deea3..fc3456e2ccb 100644
> > > > --- a/sql/field.cc
> > > > +++ b/sql/field.cc
> > > > @@ -7368,7 +7368,9 @@ bool
> > > >    Field_longstr::cmp_to_string_with_same_collation(const Item_bool_func *cond,
> > > >                                                     const Item *item) const
> > > >    {
> > > > +  Type_handler_hybrid_field_type cmp(type_handler_for_comparison());
> > >
> > > Can this be anything else but type_handler_long_blob ?
> > > if not, then I'd suggest
> > >
> > >      Type_handler_hybrid_field_type cmp(type_handler_long_blob);
> > >      DBUG_ASSERT(type_handler_for_comparison() == &type_handler_long_blob);
> >
> > Generally we don't know. It's now for every single plugin to decide.
> > One can make a plugin using Field_longstr as a base for its Field,
> > but with a different comparison type handler.
> >
> > I wrote it in a generic way which should work for all cases.
>
> Yes, I know. But practically we won't have such plugins for quite a
> while, so I'd rather prefer a shorter execution path and a faster code.
> And an assert that will remind us to implement your gneralized approach
> when the assumption will be broken.

This code is not heavily loaded and should not affect performance.
I prefer the generic way.



> > > One more question. What type do we have where you need to aggregate here
> > > and simple
> > >
> > >      item->type_handler_for_comparison() != &type_handler_long_blob
> > >
> > > won't do?
> >
> > We don't know. It's for a plugin to decide if its data type
> > is stronger of weaker than CHAR/VARCHAR/TEXT.
> > For INET6 and UUID we decided they are stronger.
> > But eventually we may want to add some weaker data type.
>
> Same here.
>
> Regards,
> Sergei
> VP of MariaDB Server Engineering
> and security@xxxxxxxxxxx