set hive.merge.mapfiles=true; set hive.merge.mapredfiles=true; set hive.merge.sparkfiles=true; set mapred.min.split.size=256; set mapred.min.split.size.per.node=256; set mapred.min.split.size.per.rack=256; set mapred.max.split.size=256; -- SORT_QUERY_RESULTS create table test1(key int, val int); explain insert overwrite table test1 select key, count(1) from src group by key; insert overwrite table test1 select key, count(1) from src group by key; select * from test1; drop table test1; create table test_src(key string, value string) partitioned by (ds string); create table test1(key string); insert overwrite table test_src partition(ds='101') select * from src; insert overwrite table test_src partition(ds='102') select * from src; explain insert overwrite table test1 select key from test_src; insert overwrite table test1 select key from test_src; set hive.merge.smallfiles.avgsize=16; explain insert overwrite table test1 select key from test_src; insert overwrite table test1 select key from test_src;