Doc db_sync --expand incurring downtime in upgrades to Newton
Doc db_sync --expand incurring downtime in upgrades to Newton

The current implementation of db_sync --expand automatically runs any
outstanding legacy operations to ensure it's safety. However, that
behavior also means that legacy migrations may violate the safety
assumptions around --expand.

This is only true for Mitaka to Newton upgrades, as there should not be
any newer migrations in the legacy repository to be triggered by this
behavior.

[1] https://github.com/openstack/keystone/blob/0ebd557325ff16c2535dac0eb190792e6d511a79/keystone/common/sql/upgrades.py#L269-L271

Change-Id: Ib175f7fce96011d77eb4783123cb2d265d60aa42
Closes-Bug: 1676925

ilay09/keystone,openstack/keystone,ilay09/keystone,openstack/keystone,ilay09/keystone,mahak/keystone,mahak/keystone,rajalokan/keystone,rajalokan/keystone,rajalokan/keystone,openstack/keystone,mahak/keystone