maria-developers team mailing list archive

[Sergey Vojtovich <svoj@xxxxxxxxxxx>]

Hi Sergei,

On Tue, Mar 04, 2014 at 01:10:19PM +0100, Sergei Golubchik wrote:
> Hi, Sergey!
> 
> On Feb 14, Sergey Vojtovich wrote:
> > At lp:maria/10.0
> > 
> > ------------------------------------------------------------
> > revno: 4006
> > revision-id: svoj@xxxxxxxxxxx-20140214122541-tenvcllk760deai8
> > parent: svoj@xxxxxxxxxxx-20140213071355-psk0jpsarx2u7myc
> > committer: Sergey Vojtovich <svoj@xxxxxxxxxxx>
> > branch nick: 10.0
> > timestamp: Fri 2014-02-14 16:25:41 +0400
> > message:
> >   MDEV-5674 - Performance: my_hash_sort_bin is called too often
> >   
> >   - reduced number of my_hash_sort_bin() calls from 4 to 2 per query.
> >     Let MDL subsystem use pre-calculated hash value for hash
> >     inserts and deletes.
> 
> Is this necessary? One of the reasons why I didn't review this your first patch,
> because I believed that the second one obsoletes it.
> 
> Why do you need my_hash_insert_using_hash_value() when you achieve the
> same effect with your calc_hash callback in the second patch
Currently yes, because in one case key is char string (no MDL_key is available)
and in another case MDL_key is available by offset juggling. But I think I can
avoid it. I'll try and get back to you with updated patch.

> >   - reduced number of memory accesses done by my_hash_sort_bin()
> 
> I'd expect the compiler to handle it automatically, but feel free to
> change it, if it doesn't.
It was tested and unfortunately compiler didn't handle it.

Thanks,
Sergey