Re: [sqlsmith] Failed assertion in parallel worker in ExecInitSubPlan

On Sun, Nov 20, 2016 at 10:43 PM, Andreas Seltenreich
<seltenreich@gmx.de> wrote:
> Hi,
>
> the query below triggers a parallel worker assertion for me when run on
> the regression database of master as of 0832f2d.  The plan sports a
> couple of InitPlan nodes below Gather.
>

I think the reason of this issue is that in some cases where subplan
is at some node other than top_plan node, we allow them to be executed
in the worker in force_parallel_mode.  It seems to me that the
problematic code is below check in standard_planner()

if (force_parallel_mode != FORCE_PARALLEL_OFF &&
best_path->parallel_safe &&
top_plan->initPlan == NIL)

Here instead of checking whether top_plan has initPlan, it should
check whether initPlan is present anywhere in plan tree.  I think one
simple way could be to check *glob->subplans* instead of
top_plan->initPlan, another possibility is to traverse the whole tree
to see if initPlan is present.

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