maria-developers team mailing list archive

[Sergei Petrunia <psergey@xxxxxxxxxxxx>]

An alternative patch:

=== modified file 'sql/item_sum.cc'
--- sql/item_sum.cc     2013-02-28 17:42:49 +0000
+++ sql/item_sum.cc     2013-03-25 16:15:05 +0000
@@ -1539,7 +1539,8 @@
 
 bool Item_sum_count::add()
 {
-  if (!args[0]->maybe_null || !args[0]->is_null())
+  //if (!args[0]->maybe_null || !args[0]->is_null())
+  if (!aggr->arg_is_null())
     count++;
   return 0;
 }


Any reason this will not work?

On Sun, Mar 24, 2013 at 10:20:41AM -0700, Igor Babaev wrote:
> On 03/24/2013 08:37 AM, Sergei Golubchik wrote:
> > Hi, Igor!
> > 
> > On Mar 22, Igor Babaev wrote:
> >> At file:///home/igor/maria/maria-5.5-bug4311/
> >>
> >> ------------------------------------------------------------
> >> revno: 3701
> >> revision-id: igor@xxxxxxxxxxxx-20130322224651-r2tpn9in5i1ifv7a
> >> parent: sergii@xxxxxxxxx-20130317104125-yyp99euwpir5ueho
> >> committer: Igor Babaev <igor@xxxxxxxxxxxx>
> >> branch nick: maria-5.5-bug4311
> >> timestamp: Fri 2013-03-22 15:46:51 -0700
> >> message:
> >>   Fixed bug mdev-4311 (bug #68749).
> >>   This bug was introduced by the patch for WL#3220.
> >>   If the memory allocated for the tree to store unique elements
> >>   to be counted is not big enough to include all of them then
> >>   an external file is used to store the elements.
> >>   The unique elements are guaranteed not to be nulls. So, when 
> >>   reading them from the file we don't have to care about the null
> >>   flags of the read values. However, we should remove the flag 
> >>   at the very beginning of the process. If we don't do it and
> >>   if the last value written into the record buffer for the field
> >>   whose distinct values needs to be counted happens to be null,
> >>   then all values read from the file  are considered to be nulls
> >>   and are not counted in.
> >>   The fix does not remove a possible null flag for the read values.
> >>   Rather it just counts the values in the same way it was done
> >>   before WL #3220.
> > 
> >> === modified file 'sql/item_sum.cc'
> >> --- a/sql/item_sum.cc	2013-02-28 17:42:49 +0000
> >> +++ b/sql/item_sum.cc	2013-03-22 22:46:51 +0000
> >> @@ -1460,6 +1460,12 @@
> >>    
> >>  bool Aggregator_distinct::unique_walk_function(void *element)
> >>  {
> >> +  if (item_sum->sum_func() == Item_sum::COUNT_DISTINCT_FUNC)
> >> +  {
> >> +    Item_sum_count *sum= (Item_sum_count *)item_sum;
> >> +    sum->count++;
> >> +    return 0;
> >> +  }
> >>    memcpy(table->field[0]->ptr, element, tree_key_length);
> >>    item_sum->add();
> >>    return 0;
> > 
> > I'm not sure I like it. You've added a special check for
> > COUNT_DISTINCT_FUNC just before the call of item_sum->add() which is
> > virtual, and Item_sum_count has its own implementation of it. Logically,
> > if there's a virtual method, the check should be in there, not in the
> > caller.
> 
> I don't see any problem here because
> Aggregator_distinct::unique_walk_function
> is not virtual.
> Actually here we have two 'implementations' of the
> Aggregator_distinct::unique_walk_function processor.
> One of them is used only for COUNT(DISTINCT) items.
> 
> Currently Sergey Petrunia is already fighting with unnecessary virtual
> functions in these classes. I remove one of them, that is good.
> 
> Regards,
> Igor.
> 
> > 
> > And what about SUM(DISTINCT ...) ?
> > 
> > Perhaps it's better to mark the item not null, as you've explained in
> > the changeset comment?
> > 
> > Regards,
> > Sergei
> 
> 
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-- 
BR
 Sergei
-- 
Sergei Petrunia, Software Developer
Monty Program AB, http://askmonty.org
Blog: http://s.petrunia.net/blog