SQL - improve NOT EXISTS query performance

Question

Is there a way I can improve this kind of SQL query performance:

INSERT
INTO ...
WHERE NOT EXISTS(Validation...)

The problem is when I have ma

Answer 1

If you can at all reduce your problem space, then you'll gain heaps of performance. Are you absolutely sure that every one of those rows in that table needs to be checked?

The other thing you might want to try is a DELETE InsertTable FROM InsertTable INNER JOIN ExistingTable ON before your insert. However, your mileage may vary