Comment 4 for bug 1419239

Reviewed: https://review.openstack.org/154530
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=989fac5c5821739fef4809b0d75840e3bc4685bf
Submitter: Jenkins
Branch: stable/juno

commit 989fac5c5821739fef4809b0d75840e3bc4685bf
Author: ZhiQiang Fan <email address hidden>
Date: Sat Feb 7 16:23:20 2015 +0800

    metering data ttl sql backend breaks resource metadata

    The implementation for sql clear_expired_metering_data() uses delete()
    on join() for four metatada tables, which will cause clear whole
    tables no matter what join returns. And it associates metadata id
    with sample id which makes no sense, the metadata id is resource's
    internal id.

    Change-Id: I98219bf27a0a765838d45386b7ae6b6b980b1ae9
    Closes-Bug: #1419239
    (cherry picked from commit 5a65b4de0fe46967e76832c2acf4924a53b18612)