set hive.map.aggr=true; set hive.groupby.skewindata=true; explain select count(1) from src x where x.key > 9999; select count(1) from src x where x.key > 9999; set hive.map.aggr=true; set hive.groupby.skewindata=false; explain select count(1) from src x where x.key > 9999; select count(1) from src x where x.key > 9999; set hive.map.aggr=false; set hive.groupby.skewindata=true; explain select count(1) from src x where x.key > 9999; select count(1) from src x where x.key > 9999; set hive.map.aggr=false; set hive.groupby.skewindata=false; explain select count(1) from src x where x.key > 9999; select count(1) from src x where x.key > 9999;