Regenerate UserId's UUID

[Skrypt]

For GDPR compliance it might be necessary that the Owner field always use a UUID.
In that case, if you migrated your database from RC2 you might want to regenerate UUID's on the UserId field.
Here is an example of how to do this with SQL Server, it may require other steps if you have custom Indexes.
Also, will require that you rebuild your Lucene indices afterward.

-- Assign Users with a UUID UserId

DECLARE @count int
DECLARE @i int = 1
DECLARE @Migrate bit = 1
DECLARE @DocumentId int
DECLARE @NormalizedUserName nvarchar(255)
DECLARE @UserId nvarchar(26)

IF(@Migrate = 1)
BEGIN
	SET @count = (SELECT COUNT(*) FROM UserIndex)
	SET @i = 1
	WHILE(@i <= @count)
	BEGIN
		WITH OrderedUserIndex AS
		(
			SELECT DocumentId, NormalizedUserName,
			ROW_NUMBER() OVER (ORDER BY Id) AS 'RowNumber'
			FROM UserIndex
		)
		SELECT @DocumentId = DocumentId, @NormalizedUserName = NormalizedUserName FROM OrderedUserIndex WHERE RowNumber = @i
		SET @UserId = LEFT(LOWER(REPLACE(NEWID(), '-', '')), 26)

		UPDATE UserIndex SET UserId = @UserId WHERE DocumentId = @DocumentId

		-- We update Users in the Document table
		UPDATE Document
		SET Content = JSON_MODIFY(Content, '$.UserId', @UserId)
		WHERE Id = @DocumentId

		-- We add UUID UserId on all ContentItems in Document table
		UPDATE Document
		SET Content = JSON_MODIFY(Content, '$.Owner', @UserId)
		WHERE Type = 'OrchardCore.ContentManagement.ContentItem, OrchardCore.ContentManagement.Abstractions'
		AND JSON_VALUE(Content, '$.Owner') = REPLACE(@NormalizedUserName, '+', '@')

		SELECT @i = @i + 1
	END
END

UPDATE ContentItemIndex SET Owner = (SELECT JSON_VALUE(Content, '$.Owner') FROM Document WHERE Id = ContentItemIndex.DocumentId)

-- Change SuperUser in sitesettings (change 'ADMIN' for your superuser username here)

UPDATE Document SET Content = JSON_MODIFY(Content, '$.SuperUser', (SELECT UserId FROM UserIndex WHERE NormalizedUserName = 'ADMIN'))
WHERE Type = 'OrchardCore.Settings.SiteSettings, OrchardCore.Settings'

You can adapt this SQL query to modify also the Author field in your database at the same time.
We may discuss further GDPR compliance here.

Thanks