OOM-killer issue when updating a inheritance table which has large number of child tables

Hi

In my test(PG9.3.4), i found when update a parent table which has a large number of child tables, the execute plan will consume lots of memory. And possibly cause OOM.

For example:

 create table maintb(id int,name char(10));

 create table childtb_1 (CHECK ( id BETWEEN 1 AND 200)) inherits(maintb);

 create table childtb_2 (CHECK ( id BETWEEN 201 AND 400)) inherits(maintb);

 ...

 create table childtb_n ...

When there are 100 child tables,the following update statement will consume about 8MB memory when invoking pg_plan_queries()

update maintb set name = 'aaaaa12345' where id=1;

And, when there are 1000 child tables,the same update statement will consume 717MB memory when invoking pg_plan_queries().

Does this a known problem, and could that be improved in the future?

BTW:

The following comment is according my debuging when update the parent table with 1000 child tables

src/backend/optimizer/plan/planner.c

static Plan *

inheritance_planner(PlannerInfo *root)

{

...

    foreach(lc, root->append_rel_list)//### loop 1001 time

    {

...

        subroot.parse = (Query *)

            adjust_appendrel_attrs(root,

                                 (Node *) parse,

                                 appinfo);//### allocate about 300KB memory a time.

...

        subroot.append_rel_list = (List *) copyObject(root->append_rel_list);//### allocate about 400KB memory a time.

...

    }

...

}

Best Regards

Chen Huajun