Miss index on reservations lead to slow and error

[wuyuting]

While investigating the performance issues of cinder under high concurrent pressure and large-scale environment. we discovered that there is no combined index on deleted and uuid for the reservations table. When this table gets large（> 400,000）, create/delete volumes/snapshots will become slow. Under high concurrent pressure, the client maybe timeout because of the slow process. We need to add a combined index of uuid and deleted.

| reservations | 1 | reservations_deleted_uuid_idx | 1 | deleted | A | 200 | NULL | NULL | YES | BTREE | | |
| reservations | 1 | reservations_deleted_uuid_idx | 2 | uuid | A | 200 | NULL | NULL | | BTREE | | |

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/275047

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean McGinnis (<email address hidden>) on branch: master
Review: https://review.openstack.org/275047
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[Sean McGinnis (sean-mcginnis)]

Unassigning due to no activity for > 6 months.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/275047
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=12819a1b6d78f253f795e7992b93ebfb8347e884
Submitter: Zuul
Branch: master

commit 12819a1b6d78f253f795e7992b93ebfb8347e884
Author: wuyuting <email address hidden>
Date: Tue Feb 2 02:33:35 2016 -0500

    Add index for reservations on (deleted, uuid)

    The query for uuid_reservations currently does a full table scan.
    This adds an index so frequent invocations of uuid does not bog
    down the database.

    Change-Id: I149a9de82fc1003b88e0c0852a0b64634f0c622e
    Closes-Bug: #1540750

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinder 12.0.0.0b2 development milestone.