Re: server crashed with TRAP: FailedAssertion("!(!parallel_aware || pathnode->path.parallel_safe)"

On Thu, Jun 14, 2018 at 9:54 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com> writes:
>> I am getting a server crash for below test case.
>
>> postgres=# CREATE TABLE test( c1 int, c2 int, c3 text) partition by
>> range(c1);
>> CREATE TABLE
>> postgres=# create table test_p1 partition of test for values from
>> (minvalue) to (0);
>> CREATE TABLE
>> postgres=# create table test_p2 partition of test for values from (0) to
>> (maxvalue);
>> CREATE TABLE
>> postgres=#
>> postgres=# select (select max((select t1.c2 from test t1 where t1.c1 =
>> t2.c1))) from test t2;
>> server closed the connection unexpectedly
>
> Reproduced here. The assert seems to be happening because
> add_paths_to_append_rel is trying to create a parallel path for
> an appendrel that is marked consider_parallel = false.
>
> This appears to be the fault of commit ab7271677, whose authors I've cc'd:
> the stanza starting at about allpaths.c:1672 is bullheadedly creating a
> parallel path whether that's allowed or not. Fixing it might be as simple
> as adding "rel->consider_parallel" to the conditions there.
>

Yeah, or perhaps disallow creation of any partial paths at the first
place like in attached. This will save us some work as well.

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