Re: [sqlsmith] Failed assertion in create_gather_path - Mailing list pgsql-hackers

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?

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.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com