Remove SQL's datetime format inplace of integer timestamps

[Lance Bragstad]

Keystone's current schema uses SQL's DATETIME format. Depending on the version of SQL (before or after v5.6.4), it may or may not support sub-second accuracy/precision.

> A DATETIME or TIMESTAMP value can include a trailing fractional seconds part in up to microseconds (6 digits) precision. In particular, as of MySQL 5.6.4, any fractional part in a value inserted into a DATETIME or TIMESTAMP column is stored rather than discarded.

Source: https://dev.mysql.com/doc/refman/5.6/en/datetime.html

We should replace keystone's use of DATETIME with an integer timestamp. With integer timestamps we can support sub-second accuracy regardless of the version of SQL being used.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/243742

[Boris Bobrov (bbobrov)]

Silly launchpad doesn't let me assign it back to Lance, so I'm just removing assignee.

[Lance Bragstad (lbragstad)]

This topic was discussed at the Keystone Mitaka Midcycle in Austin and I don't think this applies anymore. This could be closed by - https://review.openstack.org/#/c/275497/

[OpenStack Infra (hudson-openstack)]

Change abandoned by Lance Bragstad (<email address hidden>) on branch: master
Review: https://review.openstack.org/243742
Reason: According to conversations at the mid-cycle, we are going to abandon the pursuit of sub-second precision in keystone [0]. This would be an unnecessary migration causing operator pain without a justified reason.

[0] https://review.openstack.org/#/c/275497/

[Steve Martinelli (stevemar)]

Marking this as invalid since the change was abandoned by the bug originator. Thanks Lance :)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/tempest 11.0.0 release.