Hive_HIVE Optimization Guide_Scenario 6_By letting the MAP end, take more tasks to reduce the computational cost and data transmission cost of Reducer

Outline address:  https://blog.csdn.net/u010003835/article/details/105334641

 

Test Data 

 

 

 

 

 

Scenario 6. Reduce the computational cost and data transmission cost of the reducer by letting the MAP end perform more tasks.

1) The way of MAP JOIN

 

 

 

2) MAP AGGR, pre-aggregation on the Map side