Query Performance with [side].[sync_row_is_tombstone] = 1 - Can we use UNION instead?

[florianendrich]

Hi,

i'm currently writting a AddCustomWhere which itselfs joins a lot of tables to do the filtering like WHERE Id IN (<SubQuery>).
Now on AddCustomWhere - and in AddWhere the Code is using (or is suggesting to use) {{{side}}}.{{{sync_row_is_tombstone}}} = 1 to retreive all deleted rows for sync.

However this causes my query to run forever instead of returning in like 4 seconds. There is only 1 deleted row currently.

Now i was wondering if we could simply always add something like this:

UNION
SELECT
	  [side].[Id]
	  [...]
	, [side].[sync_row_is_tombstone] as [sync_row_is_tombstone]
FROM [Mdb].[Assets] [base]
RIGHT JOIN [Assets_tracking] [side] ON [base].[Id] = [side].[Id]
WHERE ([side].[sync_row_is_tombstone] = 1)

at the end of the WHERE clauses.
Which should actually result in the same result - simply including all deleted rows?

Im also wondering why this is actually done in the initialize SP but missing in the changes SP?