(perf) Unnecessarily joining instance.services when listing instances regardless of microversion

[Matt Riedemann]

Microversion 2.16 adds the ability to show the host status of an instance when listing servers with details or showing a single server's details. By default that is only shown for an admin.

Change https://review.openstack.org/#/c/355558/ helped improve the performance for this by avoiding lazy-loading the instance.services column by doing the join in the DB API when querying the instances from the database.

However, that check is not based on version 2.16, like the 2.26 tags check below it.

This means that we are unnecessarily joining with the services table when querying instances with microversions < 2.16, which happens, for example, by default in the openstack CLI which uses microversion 2.1.

We arguably should make this also conditional on policy so we don't join for non-admins by default, but that's less of an issue probably as non-admins probably aren't listing thousands of instances from the deployment like an admin would.

[Matt Riedemann (mriedem)]

Related patch: https://review.openstack.org/#/c/507854/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/507854
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=a0b4116ed68cb71a9a74fee616b5036f5fda4dd2
Submitter: Zuul
Branch: master

commit a0b4116ed68cb71a9a74fee616b5036f5fda4dd2
Author: Andrey Volkov <email address hidden>
Date: Wed Sep 27 09:40:22 2017 +0300

    List instances performace optimization

    Join service table for microversion starting 2.16 only
    so only include service from 2.16 version.

    Co-Authored-By: jichenjc <email address hidden>

    Closes-Bug: 1719460

    Change-Id: I6c57fa013ee8f6d064fc747906e1234a0aa3e8c2

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/queens
Review: https://review.openstack.org/561715

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/561715
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=9cb96ab9319aea2e63c0c67cab9e5d92638bfcb2
Submitter: Zuul
Branch: stable/queens

commit 9cb96ab9319aea2e63c0c67cab9e5d92638bfcb2
Author: Andrey Volkov <email address hidden>
Date: Wed Sep 27 09:40:22 2017 +0300

    List instances performace optimization

    Join service table for microversion starting 2.16 only
    so only include service from 2.16 version.

    Co-Authored-By: jichenjc <email address hidden>

    Closes-Bug: 1719460

    Change-Id: I6c57fa013ee8f6d064fc747906e1234a0aa3e8c2
    (cherry picked from commit a0b4116ed68cb71a9a74fee616b5036f5fda4dd2)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 18.0.0.0b1 development milestone.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 17.0.3 release.