GetGroupKey evaluates the group items and args of aggregate functions.

AfFinalResult indicates aggregation functions final result.

AggSpillDiskAction implements memory.ActionOnExceed for unparalleled HashAgg.

AggWorkerInfo contains the agg worker information.

AggWorkerStat record the AggWorker runtime stat.

HashAggExec deals with all the aggregate functions.

HashAggFinalWorker indicates the final workers of parallel hash agg execution, the number of the worker can be set by `tidb_hashagg_final_concurrency`.

HashAggInput indicates the input of hash agg exec.

HashAggPartialWorker indicates the partial workers of parallel hash agg execution, the number of the worker can be set by `tidb_hashagg_partial_concurrency`.

HashAggRuntimeStats record the HashAggExec runtime stat.

ParallelAggSpillDiskAction implements memory.ActionOnExceed for parallel HashAgg.

StreamAggExec deals with all the aggregate functions.