Re: [sqlsmith] Failed assertion in create_gather_path
| От | Jeevan Chalke |
|---|---|
| Тема | Re: [sqlsmith] Failed assertion in create_gather_path |
| Дата | |
| Msg-id | CAM2+6=Udi4nZa3y7W_EX-VE5wKzwzyvDtS2SQ2fj0uG1KxzMPw@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: [sqlsmith] Failed assertion in create_gather_path (Amit Kapila <amit.kapila16@gmail.com>) |
| Ответы |
Re: [sqlsmith] Failed assertion in create_gather_path
|
| Список | pgsql-hackers |
On Mon, Apr 9, 2018 at 5:52 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
In recurse_set_operations() we are building a new rel and setting its properties from the final_rel. consider_parallel there is just copied from the final_rel.
However, in set_subquery_pathlist(), rel is the input parameter here and we are trying to add a partial path to it without looking at its consider_parallel field. This patch does that.
And if we want to set consider_parallel for the rel, then it should have been done prior to this function itself. And I am not sure where that exactly but not in this function I guess.
I actually wanted to have rel->consider_parallel in the condition (yes, for additional safety) as we are adding a partial path into rel. But then observed that it is same as that of final_rel->consider_parallel and thus used it along with other condition.
I have observed at many places that we do check consider_parallel flag before adding a partial path to it. Thus for consistency added here too, but yes, it just adds an additional safety here.
On Sun, Apr 8, 2018 at 1:04 PM, Jeevan Chalke
<jeevan.chalke@enterprisedb.com> wrote:
> Hi,
>
> At some places, I have observed that we are adding a partial path even when
> rel's consider_parallel is false. Due to this, the partial path added has
> parallel_safe set to false and then later in create_gather_path() assertion
> fails.
>
Few Comments:
1.
@@ -2196,6 +2196,10 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
pathkeys, required_outer));
}
+ /* If parallelism is not possible, return. */
+ if (!rel->consider_parallel || !bms_is_empty(required_outer))
+ return;
In this case shouldn't we set the rel's consider_parallel flag
correctly rather than avoiding adding the path to it as we do in
recurse_set_operations?
In recurse_set_operations() we are building a new rel and setting its properties from the final_rel. consider_parallel there is just copied from the final_rel.
However, in set_subquery_pathlist(), rel is the input parameter here and we are trying to add a partial path to it without looking at its consider_parallel field. This patch does that.
And if we want to set consider_parallel for the rel, then it should have been done prior to this function itself. And I am not sure where that exactly but not in this function I guess.
2.
@@ -331,7 +331,7 @@ recurse_set_operations(Node *setOp, PlannerInfo *root,
* to build a partial path for this relation. But there's no point in
* considering any path but the cheapest.
*/
- if (final_rel->partial_pathlist != NIL)
+ if (final_rel->consider_parallel && final_rel->partial_pathlist != NIL)
What problem did you see here or is it just for additional safety?
Ideally, if the consider_parallel is false for a rel, it's partial
path list should also be NULL.
I actually wanted to have rel->consider_parallel in the condition (yes, for additional safety) as we are adding a partial path into rel. But then observed that it is same as that of final_rel->consider_parallel and thus used it along with other condition.
I have observed at many places that we do check consider_parallel flag before adding a partial path to it. Thus for consistency added here too, but yes, it just adds an additional safety here.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
--
Jeevan Chalke
Technical Architect, Product Development
EnterpriseDB Corporation
The Enterprise PostgreSQL Company
Technical Architect, Product Development
EnterpriseDB Corporation
The Enterprise PostgreSQL Company
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