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

On Mon, Sep 11, 2017 at 5:19 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Mon, Sep 11, 2017 at 6:45 AM, Ashutosh Bapat
> <ashutosh.bapat@enterprisedb.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       | tvirtualxid |          | 4/4        | 4/4                | 50914 |
ExclusiveLock   | t       | trelation   | t1p1p1   |            | 3/12               | 50912 |
AccessShareLock | t       | trelation   | t1p1     |            | 3/12               | 50912 |
AccessShareLock | t       | trelation   | t1       |            | 3/12               | 50912 |
AccessShareLock | t       | tvirtualxid |          | 3/12       | 3/12               | 50912 |
ExclusiveLock   | t       | t
(6 rows)

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


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