optimize queries for image-list

[Venkatesh Sampath]

Get image list take lot of time for certain image-list criterias. Found through the explain plan and slow query logs that there is a full table scan happening on certain scenarios.

The fix is to refactor the get_image_list query building code to avoid full table scan and hence reduce the response time taken.

As part of the optimization of query the following fixes are to be done:
- avoid full table scan on images table by converting,
  images.is_public = 1 OR images.owner = 'OWNER'
  to
  query WHERE images.is_public = 1
  UNION
  query WHERE images.owner = 'OWNER'
- introduce missing index for owner column on images table.
- move image related conditions to the inner union queries
- remove unwanted union of queries in case of admin querying for image list
- change the condition images.status != 'killed' to images.status in ('active', 'saving', 'queued', 'pending_delete', 'deleted')
- convert the correlation subqueries that are used for image_property filters into inner joins

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/41404

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/43101

[Venkatesh Sampath (venkateshsampath)]

Final fix proposed and review done is at the following location:
https://review.openstack.org/#/c/41404/

PS: This patch is dependent on a merged patch:
https://review.openstack.org/#/c/44801/9

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/41404
Committed: http://github.com/openstack/glance/commit/0e262d1ec7f5c7073a6d9f1d7bfadc3777b62297
Submitter: Jenkins
Branch: master

commit 0e262d1ec7f5c7073a6d9f1d7bfadc3777b62297
Author: Venkatesh Sampath <email address hidden>
Date: Wed Aug 21 16:59:10 2013 +0530

    optimize queries for image-list

    - avoid full table scan on images table by converting,
    images.is_public = 1 OR images.owner = 'OWNER'
    to
    query WHERE images.is_public = 1
    UNION
    query WHERE images.owner = 'OWNER'
    - move image related conditions to the inner union queries
    - remove unwanted union of queries in case of admin querying for image list
    - change the condition images.status != 'killed' to images.status in ('active', 'saving', 'queued', 'pending_delete', 'deleted')
    - convert the correlation subqueries that are used for image_property filters into inner joins

    Fixes bug 1211315

    depends on bug 1214830

    Change-Id: Ie7458044edbe1ef64871bcf5ef4996ed3cc0f957