maria-developers team mailing list archive

[Sergey Vojtovich <svoj@xxxxxxxxxxx>]

Hi Sergei,

On Tue, Mar 04, 2014 at 01:05:33PM +0100, Sergei Golubchik wrote:
> Hi, Sergey!
> 
> On Mar 03, Sergey Vojtovich wrote:
> > > > === modified file 'sql/mdl.cc'
> > > > --- a/sql/mdl.cc	2014-02-14 12:25:41 +0000
> > > > +++ b/sql/mdl.cc	2014-02-20 07:25:33 +0000
> > > > @@ -760,13 +760,22 @@ void MDL_map::init()
> > > >  }
> > > >  
> > > >  
> > > > +my_hash_value_type mdl_hash_function(const CHARSET_INFO *cs,
> > > > +                                     const uchar *key, size_t length)
> > > > +{
> > > > +  return *((my_hash_value_type*) (key - offsetof(MDL_key, m_ptr) +
> > > > +                                        offsetof(MDL_key, m_hash_value))) +
> > > > +                                       key[0];
> > > 
> > > I'd prefer to avoid pointer and offset juggling. Because you use a
> > > custom hash function anyway, you can directly pass MDL_key as your
> > > "key", then here you can use ((MDL_key*)key)->hash_value()
> > I'd prefer to avoid it too. But there is hashcmp() function which is called
> > when there are many records in a hash bucket. It does my_strnncoll() and
> > MDL_key as it is now is not good for strnncoll.
> 
> But hashcmp() uses HASH::get_key() callback to get the key.
> You can use it to return MDL_key::m_ptr
That's how it is now and that's the reason for this juggling. :)
I.e. my_hash_first_from_hash_value():
- calls hashcmp(key) which assumes key is MDL_key::m_ptr
- calls my_hash_rec_mask()/hash_function(key) which should assume key is MDL_key

Regards,
Sergey