SQL Server Stream Aggregate vs Hash match Aggregate
Hello, I am a new SQL Server engineer. While looking at the execution plan of a query that SUM() values of int type based on the range of a date column of datetime type, I discovered that SUM() processing is handled by Stream Aggregate and Hash match aggregate in each case. The table is composed of a Clustered Index with Date as the key. I think it changes to Hash match processing as the index search range increases, but I don't know the difference between the two processing methods and what criteria determine the processing method. Can you give me a good answer?