I got this crash running sqlsmith:
#1 0x00007f907574b801 in __GI_abort () at abort.c:79
#2 0x00005646b95a35f8 in ExceptionalCondition
(conditionName=conditionName@entry=0x5646b97411db "bms_num_members(varnos) ==
1", errorType=errorType@entry=0x5646b95fa00b "FailedAssertion",
fileName=fileName@entry=0x5646b9739dbe "selfuncs.c",
lineNumber=lineNumber@entry=3332) at assert.c:69
#3 0x00005646b955c9a1 in add_unique_group_expr (vars=0x5646bbd9e200,
expr=0x5646b9eb0c30, exprinfos=0x5646bbd9e100, root=0x5646ba9a0cb0) at
selfuncs.c:3332
#4 add_unique_group_expr (root=0x5646ba9a0cb0, exprinfos=0x5646bbd9e100,
expr=0x5646b9eb0c30, vars=0x5646bbd9e200) at selfuncs.c:3307
#5 0x00005646b955d560 in estimate_num_groups () at selfuncs.c:3558
#6 0x00005646b93ad004 in create_distinct_paths (input_rel=<optimized out>,
root=0x5646ba9a0cb0) at planner.c:4808
#7 grouping_planner () at planner.c:2238
#8 0x00005646b93ae0ef in subquery_planner (glob=glob@entry=0x5646ba9a0b98,
parse=parse@entry=0x5646ba905d80, parent_root=parent_root@entry=0x0,
hasRecursion=hasRecursion@entry=false, tuple_fraction=tuple_fraction@entry=0)
at planner.c:1024
#9 0x00005646b93af543 in standard_planner (parse=0x5646ba905d80,
query_string=<optimized out>, cursorOptions=256, boundParams=<optimized out>)
at planner.c:404
#10 0x00005646b94873ac in pg_plan_query (querytree=0x5646ba905d80,
query_string=0x5646b9cd87e0 "select distinct \n \n
pg_catalog.variance(\n
cast(pg_catalog.pg_stat_get_bgwriter_timed_checkpoints() as int8)) over
(partition by subq_0.c2 order by subq_0.c0) as c0, \n subq_0.c2 as c1, \n
sub"..., cursorOptions=256, boundParams=0x0) at postgres.c:821
#11 0x00005646b94874a1 in pg_plan_queries (querytrees=0x5646baaba250,
query_string=query_string@entry=0x5646b9cd87e0 "select distinct \n \n
pg_catalog.variance(\n
cast(pg_catalog.pg_stat_get_bgwriter_timed_checkpoints() as int8)) over
(partition by subq_0.c2 order by subq_0.c0) as c0, \n subq_0.c2 as c1, \n
sub"..., cursorOptions=cursorOptions@entry=256,
boundParams=boundParams@entry=0x0) at postgres.c:912
#12 0x00005646b9487888 in exec_simple_query () at postgres.c:1104
2021-03-24 03:06:12.489 CDT postmaster[11653] LOG: server process (PID 11696)
was terminated by signal 6: Aborted
2021-03-24 03:06:12.489 CDT postmaster[11653] DETAIL: Failed process was
running: select distinct
pg_catalog.variance(
cast(pg_catalog.pg_stat_get_bgwriter_timed_checkpoints() as
int8)) over (partition by subq_0.c2 order by subq_0.c0) as c0,
subq_0.c2 as c1,
subq_0.c0 as c2,
subq_0.c2 as c3,
subq_0.c1 as c4,
subq_0.c1 as c5,
subq_0.c0 as c6
from
(select
ref_1.foreign_server_catalog as c0,
ref_1.authorization_identifier as c1,
sample_2.tgname as c2,
ref_1.foreign_server_catalog as c3
from
pg_catalog.pg_stat_database_conflicts as ref_0
left join information_schema._pg_user_mappings as ref_1
on (ref_0.datname < ref_0.datname)
inner join pg_catalog.pg_amproc as sample_0 tablesample
system (5)
on (cast(null as uuid) < cast(null as uuid))
left join pg_catalog.pg_aggregate as sample_1 tablesample
system (2.9)
on (sample_0.amprocnum = sample_1.aggnumdirectargs )
inner join pg_catalog.pg_trigger as sample_2 tablesampl
