System Versioned (Temporal) tables in a view - sql-server

Question

I have a number of joined "system versioned" tables, e.g. Person, PhoneNumber and EmailAddress
The Person will only have one PhoneNumber and one EmailAddress at a time.
The PhoneNumber and EmailAddress will not usually be updated outside of a transaction that updates all 3 at once. (But they can be updated independently, just not in the normal scenario)
E.g. if I change the phone number, then all 3 records will be issued an update in the same transaction, hence giving them all the same "start time" in the history table.
Let's say I insert a person and then change the person's name, email address and phone number in 2 transactions:
DECLARE #Id TABLE(ID INT)
DECLARE #PersonId INT
-- Initial insert
BEGIN TRANSACTION
INSERT INTO Person (Name) OUTPUT inserted.PersonId INTO #Id VALUES ('Homer')
SELECT #PersonId = Id FROM #Id
INSERT INTO EmailAddress (Address, PersonId) VALUES ('homer#fake', #PersonId)
INSERT INTO PhoneNumber (Number, PersonId) VALUES ('999', #PersonId)
COMMIT TRANSACTION
-- Update
WAITFOR DELAY '00:00:02'
BEGIN TRANSACTION
UPDATE Person SET Name = 'Kwyjibo' WHERE PersonID = #PersonId
UPDATE EmailAddress SET Address = 'kwyjibo#fake' WHERE PersonID = #PersonId
UPDATE PhoneNumber SET Number = '000' WHERE PersonID = #PersonId
COMMIT TRANSACTION
Now I select from the view (just an inner join of the tables) using a temporal query:
SELECT * FROM vwPerson FOR SYSTEM_TIME ALL
WHERE PersonId = #PersonId
ORDER BY SysStartTime DESC
And I get returned a row for every combination of edit!
How can I query this view (if at all possible) to only return 1 row for the updates that were made in the same transaction?
I could add a WHERE clause to match all the SysStartTimes, however that would exclude those cases where a table was updated independently of the other 2.

Answer 1

Because of the independent updates, you actually first have to "reconstruct" a timeline, onto which you can join the data. A "sketch" of this follows, obviously don't have your actual table defns so untested:
;WITH AllTimes as (
SELECT PersonId,SysStartTime as ATime FROM Person
UNION
SELECT PersonId,SysEndTime FROM Person
UNION
SELECT PersonId,SysStartTime FROM EmailAddress
UNION
SELECT PersonId,SysEndTime FROM EmailAddress
UNION
SELECT PersonId,SysStartTime FROM PhoneNumber
UNION
SELECT PersonId,SysEndTime FROM PhoneNumber
), Ordered as (
SELECT
PersonId, ATime, ROW_NUMBER() OVER (PARTITION BY PersonId ORDER BY Atime) rn
FROM
AllTimes
), Intervals as (
SELECT
p1.PersonId,
o1.ATime as StartTime,
o2.ATime as EndTime
FROM
Ordered o1
inner join
Ordered o2
on
o1.PersonId = o2.PersonId and
o1.rn = o2.rn - 1
)
SELECT
* --TODO - Columns
FROM
Intervals i
inner join
Person p
on
i.PersonId = p.PersonId and
i.StartTime < p.SysEndTime and
p.SysStartTime < i.EndTime
inner join
Email e
on
i.PersonId = e.PersonId and
i.StartTime < e.SysEndTime and
e.SysStartTime < i.EndTime
inner join
PhoneNumber pn
on
i.PersonId = pn.PersonId and
i.StartTime < pn.SysEndTime and
pn.SysStartTime < i.EndTime
With appropriate filters if you just want one persons details, the optimizer will hopefully work it out. There may be additional filters for the joins that I've missed out also.
Hopefully you can see how the 3 CTEs construct the timeline. We take advantage of UNION eliminating duplicates in the first one.