maria-developers team mailing list archive

[Alexander Barkov <bar@xxxxxxxxxxx>]

Hi Igor,

Just a gentle reminder.

Thanks.

On 06/10/2015 04:59 PM, Alexander Barkov wrote:
> Hi Igor,
>
> I noticed that during Item_cond::fix_fields() and
> Item_func_between::fix_fields() update these optimizer
> related SELECT_LEX members:
>
> thd->lex->current_select->cond_count and
> thd->lex->current_select->between_count
>
> The purpose of these members is to allocate optimizer related buffers
> in:
> - update_ref_and_keys() in sql_select.cc and
> - check_func_dependency() in opt_table_elimination,cc
> and it seems they have no any other purposes..
>
>
>  From my understanding, this is a dead code and the collected values are
> never used:
>
> - cond_count and_between_count are later always initialized to 0
> before the walk(count_sargable_conds) call in update_ref_and_keys().
>
>
> - moreover, using the values collected during fix_fields() would not be
> correct to allocate optimized related buffers, because the code
> in fix_fields() does not distinguish between different query parts,
> so the items can be just a part of the SELECT list rather than a
> part of WHERE/HAVING/ON.
>
>
> Is the attached patch correct? All tests pass.
>
>
> Thanks.