I was previously downloading millions of records without encountering any timeouts. However, after adding a WHERE clause to limit the download to only a few thousand records, I am frequently facing timeouts. This has left me somewhat confused and questioning my understanding of how timeouts are applied.

If data is still being streamed by SQL Server after 30 seconds, does a timeout occur?

Is this difference in behavior certainly caused by the current execution plan performing poorly, or is there another explanation? I’m asking because without the WHERE clause, data starts streaming immediately, but this is clearly not happening with the WHERE clause in place.