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 partition have 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 values from (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
