I'm running a fairly complex T-SQL Merge statement which updates a slowly changing dimension from staging tables.
I'm noticing something weird in regards to performance.
When I run the query without an output clause, the query runs very quickly because there haven't been any changes in Staging since the last time I ran the query.
However, when I add the following:
The performance is abysmal. This is strange because the returned result set is empty anyway.
Any ideas as to why the output clause is causing this?
asked Nov 02 '11 at 08:47 AM in Default