![[assets/ex_gather.png|256]] - **Description**: Collects data from multiple nodes and consolidates it into a single node. This is often the final step in a parallel query where results from different partitions need to be combined. - **Performance**: Can introduce bottlenecks if large amounts of data are consolidated. - **Factors**: Volume of data, number of nodes, network bandwidth. - **Cost**: `network_transfer_cost * data_size + cpu_cost * data_size` - ![[assets/ex_gather_motion.svg|200]] - **Operates on**: [[Structures/Result Set]] - **Workloads**: - [[Workloads/IPC]] - [[Workloads/Sub/ExecuteGather]] - [[Workloads/Sub/ParallelFinish]] - [[Workloads/LWLock]] - [[Workloads/Sub/ParallelQueryDSA]] - [[Workloads/Sub/SharedTupleStore]]