On 15.01.2024 12:46, Andrei Lepikhov wrote:
> On 15/1/2024 13:42, Richard Guo wrote:
>>
>> On Mon, Jan 15, 2024 at 8:20 AM Alexander Korotkov
>> <aekorotkov@gmail.com <mailto:aekorotkov@gmail.com>> wrote:
>>
>> Thank you for providing the test case relevant for this code change.
>> The revised patch incorporating this change is attached. Now the
>> patchset looks good to me. I'm going to push it if there are no
>> objections.
>>
>>
>> Seems I'm late for the party. Can we hold for several more days? I'd
>> like to have a review on this patch.
> Get on board! It looks like this feature needs as much review as
> possible (likewise SJE).
>
Hi! Thank you for your work on this issue! I believe that this will help
the scheduler to make a more optimal query plan here and therefore speed
up their execution.
I have reviewed patches and noticed that we can add some code
refactoring. I have attached a diff file (group_by.diff) to this email.
The changes involve spelling corrections, renaming variables and porting
some common parts.
In addition, I have a few questions, since some points in the code
remained unclear to me.
1. I didn't understand why we have a question in the comment next to
the enable_group_by_reordering variable in
src/backend/optimizer/path/pathkeys.c file, I assumed it was spelling
and fixed it in the diff file.
2. Why do we set the variable (path = path_save) here
(add_paths_to_grouping_rel function) if we change its variable below and
we can pass path_save as a parameter?
foreach(lc2, pathkey_orderings)
{
PathKeyInfo *info = (PathKeyInfo *) lfirst(lc2);
/* restore the path (we replace it in the loop) */
path = path_save;
path = make_ordered_path(root,
grouped_rel,
path,
cheapest_path,
info->pathkeys);
if (path == NULL)
continue;
--
Regards,
Alena Rybakina
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company