[sqlalchemy] ttl function cause sample metadata query don't work

[Lan Qi song]

My local environment:

DB backend : mysql
TTL : 1800

# nova show e27446c0-7991-4405-b0f5-882bda92c1ab
+--------------------------------------+------------------------------------------------------------+
| Property | Value |
+--------------------------------------+------------------------------------------------------------+ |
......
| metadata | {"metering.stack": "46a07745-bdd5-4993-912a-94d2a9c1a9cf"} |
+--------------------------------------+------------------------------------------------------------+

# ceilometer sample-list -m cpu_util -q 'resource_id=e27446c0-7991-4405-b0f5-882bda92c1ab'
+--------------------------------------+----------+-------+---------------+------+---------------------+
| Resource ID | Name | Type | Volume | Unit | Timestamp |
+--------------------------------------+----------+-------+---------------+------+---------------------+
| e27446c0-7991-4405-b0f5-882bda92c1ab | cpu_util | gauge | 100.0775 | % | 2015-02-09T08:01:57 |
| e27446c0-7991-4405-b0f5-882bda92c1ab | cpu_util | gauge | 99.9775 | % | 2015-02-09T07:51:57 |
| e27446c0-7991-4405-b0f5-882bda92c1ab | cpu_util | gauge | 100.068333333 | % | 2015-02-09T07:41:57 |
| e27446c0-7991-4405-b0f5-882bda92c1ab | cpu_util | gauge | 100.001666667 | % | 2015-02-09T07:31:57 |
+--------------------------------------+----------+-------+---------------+------+---------------------+

# ceilometer sample-list -m cpu_util -q metadata.user_metadata.stack=46a07745-bdd5-4993-912a-94d2a9c1a9cf
+-------------+------+------+--------+------+-----------+
| Resource ID | Name | Type | Volume | Unit | Timestamp |
+-------------+------+------+--------+------+-----------+
+-------------+------+------+--------+------+-----------+

And I noticed that all the metadata table are empty. If I understand correctly, the "id" of metadata table is related to "internal_id" of resource table, but currently, the ceilometer-expired code related the "id" of metadata table to the "id" of Sample table:
https://github.com/openstack/ceilometer/blob/master/ceilometer/storage/impl_sqlalchemy.py#L362-L366

[ZhiQiang Fan (aji-zqfan)]

there aleady has a bug report and patch

https://bugs.launchpad.net/ceilometer/+bug/1419239
https://review.openstack.org/#/c/153902/

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/153950

[OpenStack Infra (hudson-openstack)]

Change abandoned by Lan Qi Song (<email address hidden>) on branch: master
Review: https://review.openstack.org/153950
Reason: Got it, thanks Zhi Qiang