Lock acquisition for partition table when setting generic plan

Hi all,

I have a question.

I did the following.
Even though I accessed one partition table(test2 table), I also acquired lo=
cks on other partition tables(test1 table).
I expected to acquire locks on the parent table(test table) and the partiti=
on table to access(test2 table).
Why does this happen?

At the first execution, to create a generic plan, I thought it was accessin=
g all partition tables.
However, the following event occur after second time too.
* Only occurs when plan_cache_mode =3D force_generic_plan.

postgres=3D# create table test(id int) partition by range (id);
CREATE TABLE
postgres=3D# create table test1 partition of test for values from (1) to (2=
);
CREATE TABLE
postgres=3D# create table test2 partition of test for values from (2) to (3=
);
CREATE TABLE
postgres=3D# prepare hoge(int) as select * from test where id =3D $1;
PREPARE
postgres=3D# set plan_cache_mode =3D force_generic_plan ;
SET
postgres=3D# begin;
BEGIN
postgres=3D# execute hoge(2);
 id=20
----
(0 rows)

postgres=3D# SELECT l.pid,l.granted,d.datname,l.locktype,relation,relation:=
:regclass,transactionid,l.mode FROM pg_locks l  LEFT JOIN pg_database d ON =
l.database =3D d.oid WHERE  l.pid !=3D pg_backend_pid() ORDER BY l.pid;
  pid  | granted | datname  |  locktype  | relation | relation | transactio=
nid |      mode      =20
-------+---------+----------+------------+----------+----------+-----------=
----+-----------------
 16921 | t       | postgres | relation   |    16562 | test2    |           =
    | AccessShareLock
 16921 | t       | postgres | relation   |    16559 | test1    |           =
    | AccessShareLock
 16921 | t       | postgres | relation   |    16556 | test     |           =
    | AccessShareLock
 16921 | t       |          | virtualxid |          |          |           =
    | ExclusiveLock
(4 rows)
=20
Regards
Naoki Yotsunaga