Re: Partition-wise join for join between (declaratively) partitioned tables

On Mon, Sep 11, 2017 at 5:19 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Mon, Sep 11, 2017 at 6:45 AM, Ashutosh Bapat
> <ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:
>> So, all partitioned partitions are getting locked correctly. Am I
>> missing something?
>
> That's not a valid test. In that scenario, you're going to hold all
> the locks acquired by the planner, all the locks acquired by the
> rewriter, and all the locks acquired by the executor, but when using
> prepared queries, it's possible to execute the plan after the planner
> and rewriter locks are no longer held.
>

I see the same thing when I use prepare and execute

Session 1
postgres=# prepare stmt as select 1 from t1 union all select 2 from t1;
PREPARE
postgres=# select pg_backend_pid();
pg_backend_pid
----------------
50912
(1 row)

postgres=# begin;
BEGIN
postgres=# execute stmt;
?column?
----------
(0 rows)

Session 2
postgres=# select locktype, relation::regclass, virtualxid,
virtualtransaction, pid, mode, granted, fastpath from pg_locks;
locktype | relation | virtualxid | virtualtransaction | pid |
mode | granted | fastpath
------------+----------+------------+--------------------+-------+-----------------+---------+----------
relation | pg_locks | | 4/4 | 50914 |
AccessShareLock | t | t
virtualxid | | 4/4 | 4/4 | 50914 |
ExclusiveLock | t | t
relation | t1p1p1 | | 3/12 | 50912 |
AccessShareLock | t | t
relation | t1p1 | | 3/12 | 50912 |
AccessShareLock | t | t
relation | t1 | | 3/12 | 50912 |
AccessShareLock | t | t
virtualxid | | 3/12 | 3/12 | 50912 |
ExclusiveLock | t | t
(6 rows)

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company