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

Hi,

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
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!>

--*logfile*
TRAP: FailedAssertion("!(!parallel_aware || pathnode->path.parallel_safe)",
File: "pathnode.c", Line: 1288)
2018-06-13 12:48:41.577 IST [52050] LOG: server process (PID 52061) was
terminated by signal 6: Aborted
2018-06-13 12:48:41.577 IST [52050] DETAIL: Failed process was running:
select (select max((select t1.c2 from test t1 where t1.c1 = t2.c1))) from
test t2;

*--core file *
Core was generated by `postgres: edb postgres [local]
SELECT '.
Program terminated with signal 6, Aborted.
#0 0x0000003dd2632495 in raise (sig=6) at
../nptl/sysdeps/unix/sysv/linux/raise.c:64
64 return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig);
Missing separate debuginfos, use: debuginfo-install
keyutils-libs-1.4-5.el6.x86_64 krb5-libs-1.10.3-65.el6.x86_64
libcom_err-1.41.12-23.el6.x86_64 libselinux-2.0.94-7.el6.x86_64
openssl-1.0.1e-57.el6.x86_64 zlib-1.2.3-29.el6.x86_64
(gdb) bt
#0 0x0000003dd2632495 in raise (sig=6) at
../nptl/sysdeps/unix/sysv/linux/raise.c:64
#1 0x0000003dd2633c75 in abort () at abort.c:92
#2 0x0000000000a32782 in ExceptionalCondition (conditionName=0xc23718
"!(!parallel_aware || pathnode->path.parallel_safe)", errorType=0xc23411
"FailedAssertion",
fileName=0xc2357d "pathnode.c", lineNumber=1288) at assert.c:54
#3 0x00000000007f1a3d in create_append_path (root=0x27a5930,
rel=0x27c25f0, subpaths=0x27c4e60, partial_subpaths=0x0,
required_outer=0x0, parallel_workers=2,
parallel_aware=true, partitioned_rels=0x27c36f0, rows=-1) at
pathnode.c:1288
#4 0x0000000000797d40 in add_paths_to_append_rel (root=0x27a5930,
rel=0x27c25f0, live_childrels=0x27c4958) at allpaths.c:1700
#5 0x00000000007d3392 in apply_scanjoin_target_to_paths (root=0x27a5930,
rel=0x27c25f0, scanjoin_targets=0x27c4558,
scanjoin_targets_contain_srfs=0x0,
scanjoin_target_parallel_safe=false, tlist_same_exprs=true) at
planner.c:6962
#6 0x00000000007cb218 in grouping_planner (root=0x27a5930,
inheritance_update=false, tuple_fraction=0) at planner.c:2014
#7 0x00000000007c943a in subquery_planner (glob=0x27855e0,
parse=0x26c7250, parent_root=0x0, hasRecursion=false, tuple_fraction=0) at
planner.c:966
#8 0x00000000007c7ff7 in standard_planner (parse=0x26c7250,
cursorOptions=256, boundParams=0x0) at planner.c:405
#9 0x00000000007c7d1f in planner (parse=0x26c7250, cursorOptions=256,
boundParams=0x0) at planner.c:263
#10 0x00000000008c461e in pg_plan_query (querytree=0x26c7250,
cursorOptions=256, boundParams=0x0) at postgres.c:809
#11 0x00000000008c4751 in pg_plan_queries (querytrees=0x27a58f8,
cursorOptions=256, boundParams=0x0) at postgres.c:875
#12 0x00000000008c4a26 in exec_simple_query (query_string=0x26c5798 "select
(select max((select t1.c2 from test t1 where t1.c1 = t2.c1))) from test
t2;") at postgres.c:1050
#13 0x00000000008c8e67 in PostgresMain (argc=1, argv=0x26ef2a0,
dbname=0x26ef100 "postgres", username=0x26c2298 "edb") at postgres.c:4153
#14 0x0000000000826657 in BackendRun (port=0x26e7060) at postmaster.c:4361
#15 0x0000000000825dc5 in BackendStartup (port=0x26e7060) at
postmaster.c:4033
#16 0x00000000008221a7 in ServerLoop () at postmaster.c:1706
#17 0x0000000000821ad9 in PostmasterMain (argc=3, argv=0x26c01f0) at
postmaster.c:1379
#18 0x0000000000748cb8 in main (argc=3, argv=0x26c01f0) at main.c:228

Thanks & Regards,
Rajkumar Raghuwanshi
QMG, EnterpriseDB Corporation