Inconsistent behaviour calling pg_try_advisory_xact_lock with sub-query and when JOIN'ing

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От	Andreas Joseph Krogh
Тема	Inconsistent behaviour calling pg_try_advisory_xact_lock with sub-query and when JOIN'ing
Дата	7 августа 2015 г. 17:27:56
Msg-id	VisenaEmail.6.7024d6d4139fd6c4.14f0932cb5d@tc7-visena обсуждение исходный текст
Ответы	Re: Inconsistent behaviour calling pg_try_advisory_xact_lock with sub-query and when JOIN'ing
Список	pgsql-general

Дерево обсуждения

Hi all.

The following query returns and locks 1 row as expected (only one row in pg_locks with locktype='advisory' and objid=sequence_id):

begin;
select qe.entity_id, qe.version, qe.queue_id, qe.sequence_id, qe.tx_id
from origo_queue_entry qe
WHERE
    qe.queue_id = (SELECT q.entity_id FROM origo_queue q WHERE q.name = 'EMAIL_IMPORT_STORE')    AND pg_try_advisory_xact_lock(sequence_id)
ORDER BY qe.sequence_id ASC
LIMIT 1 FOR UPDATE
;

But when JOIN'ing with origo_queue instead of using a sub-query:

begin;
select qe.entity_id, qe.version, qe.queue_id, qe.sequence_id, qe.tx_id
from origo_queue_entry qe JOIN origo_queue q ON q.entity_id = qe.queue_id
WHERE
    q.name = 'EMAIL_IMPORT_STORE'
    AND pg_try_advisory_xact_lock(sequence_id)
ORDER BY qe.sequence_id ASC
LIMIT 1 FOR UPDATE
;