Clustered index and non-clustered index performance

The data volume is large, and the performance is worrying. For more than 400 million records, the data aggregation speed of more than 30 million queries is 4 times faster. Note that if it is a composite index, it must be the first column, non-first column index does not work ., I remember the articles on the internet saying that clustered indexes are precious. This index must be created. Unfortunately, it is not generally understood that the index was created in the ID column, and this clustered index is wasted. 1. Use non-clustered index 2. Use clustered Index