RE: Parallel INSERT (INTO ... SELECT ...)

Hi,

I have an issue of the check about column default expressions.

+    if (command_type == CMD_INSERT)
+    {
+        /*
+         * Column default expressions for columns in the target-list are
+         * already being checked for parallel-safety in the
+         * max_parallel_hazard() scan of the query tree in standard_planner().
+         */
+
+        tupdesc = RelationGetDescr(rel);
+        for (attnum = 0; attnum < tupdesc->natts; attnum++)


IMO, max_parallel_hazard() only check the parent table's default expressions, But if the table has partitions and its
partitionhave its own default expressions, max_parallel_hazard() seems does not check that.
 
And we seems does not check that too.

I am not sure should we allow parallel insert for this case ?

Example:

-------------------------
set parallel_setup_cost=0;
set parallel_tuple_cost=0;
set min_parallel_table_scan_size=0;
set max_parallel_workers_per_gather=4;

create table origin(a int);
insert into origin values(generate_series(1,5000));

create or replace function bdefault_unsafe () returns int language plpgsql parallel unsafe as $$ begin
    RETURN 5;
end $$;

create table parttable1 (a int, b name) partition by range (a); create table parttable1_1 partition of parttable1 for
valuesfrom (0) to (5000); create table parttable1_2 partition of parttable1 for values from (5000) to (10000);
 

alter table parttable1_1 ALTER COLUMN b SET DEFAULT bdefault_unsafe();

postgres=# explain insert into parttable1 select * from origin ;
                                   QUERY PLAN                                   
--------------------------------------------------------------------------------
 Gather  (cost=0.00..41.92 rows=5865 width=0)
   Workers Planned: 3
   ->  Insert on parttable1  (cost=0.00..41.92 rows=0 width=0)
         ->  Parallel Seq Scan on origin  (cost=0.00..41.92 rows=1892 width=68)
(4 rows)

postgres=# explain insert into parttable1_1 select * from origin ;
                            QUERY PLAN                             
-------------------------------------------------------------------
 Insert on parttable1_1  (cost=0.00..1348.00 rows=0 width=0)
   ->  Seq Scan on origin  (cost=0.00..1348.00 rows=5000 width=68)
(2 rows)

-------------------------

Best regards,
houzj