- **Description**: Performs aggregation functions like SUM, AVG, COUNT, etc - **Performance**: CPU-intensive for complex aggregations. - **Factors**: Size of dataset, number of groups, aggregation complexity. - **Cost**: `cpu_tuple_cost * number of tuples + cpu_operator_cost * number of groups` - ![[assets/ex_aggregate.svg|200x200]] - **Operates on**: [[Structures/Result Set]] - **Workloads**: - [[Workloads/IO]] - [[Workloads/Sub/BufFileRead]] - [[Workloads/Sub/BufFileWrite]] - [[Workloads/LWLock]] - [[Workloads/Sub/BufferContent]]