Reduce duplicate data between unified limit tables

[Lance Bragstad]

Unified limits consists of registered limits and limits, which are project-specific. Both types are isolated into separate database tables (keystone.registered_limit and keystone.limit). The following is the existing schema for both tables:

http://paste.openstack.org/raw/723936/

There are some duplicated attributes between these two tables that are requirements for the API (e.g. a limit cannot be created without a corresponding limit being registered first). We have the opportunity to simplify the schema of the keystone.limit table by removing limit.service_id, limit.region_id, and limit.resource_name in favor of a single column called limit.registered_limit_id that maintains a FK relationship to a record in keystone.registered_limit.

The unified limit API will use the FK relationship to populate service_id, region_id, and resource_name attributes of a limit from the corresponding registered_limit.

Possibly solutions for the migration were whiteboarded using the following etherpad:

https://etherpad.openstack.org/p/keystone-unified-limit-migration-notepad

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/577751

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/577751
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=a558eb0baba05280747ea67556e1041e86898ef3
Submitter: Zuul
Branch: master

commit a558eb0baba05280747ea67556e1041e86898ef3
Author: wangxiyuan <email address hidden>
Date: Mon Jun 25 15:45:33 2018 +0800

    Add registered_limit_id column for limit

    This patch add a registered_limit_id column referring to
    the related registered limit for limit talbe.

    This change aims to reduce the duplicate data between unified
    limit tables.

    In Rocky, "registered_limit_id" will co-exist with "service_id",
    "region_id" and "resource_name" columns.

    In Stein, we'll migrate the old data to satisfy the
    "registered_limit_id" way

    In T release, the "service_id", "region_id" and "resource_name"
    columns will be removed at all.

    Closes-Bug: #1777892
    Change-Id: I9a81056b9afda924aac71f64c2158d9db53d8594

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/keystone 14.0.0.0rc1 release candidate.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/657187
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=f43954be9419e96fbe9d231aa1f5ae32cd0142eb
Submitter: Zuul
Branch: master

commit f43954be9419e96fbe9d231aa1f5ae32cd0142eb
Author: wangxiyuan <email address hidden>
Date: Sun May 5 10:39:17 2019 +0800

    Drop limit columns

    The service_id, region_id and resource_name columns in limit table
    is useless now. These info can be got by 'registered_limit_id'
    column from registered limit table. So there is no data migration
    needed.

    Since this is a silent change for end users, there is no need for
    a release note as well.

    Related-Bug: #1777892
    Change-Id: Ibf4aa81dad7c5ebbd5599a55237cc5a658223432