- **Description**: Joins tables using a hash table. - **Performance**: Efficient for large joins. - **Factors**: Size of join tables, hash table size. - **Cost**: `build cost + probe cost + cpu_operator_cost * rows joined` - ![[ex_hash_semi_join.svg|200x200]]![[ex_hash_anti_join.svg|200x200]] - **Operates on**: [[Result Set]] - **Workloads**: - [[IO]] - [[BufFileRead]] - [[BufFileWrite]] - [[LWLock]] - [[ParallelHashJoin]] - [[BufferContent]] - [[IPC]] - [[HashBuildElect]] - [[HashBuildHashInner]] - [[HashBuildHashOuter]] - [[HashBatchLoad]]