功能:将两个表中的 相同的字段拼接到一起
特点:union all不去重,数据会重复
测试:
create external table IF NOT EXISTS temp_uniontest_ta
(
a1 string,
a2 string
)
partitioned by (dt string)
row format delimited fields terminated by '\t'
stored as textfile;
ALTER TABLE temp_uniontest_ta ADD IF NOT EXISTS PARTITION (dt = '2014-10-13') location '/temp/unionTest/ta/';
a1 a2 2014-10-13
b1 b2 2014-10-13
c1 c2 2014-10-13
create external table IF NOT EXISTS temp_uniontest_tb
(
a1 string,
a2 string
)
partitioned by (dt string)
row format delimited fields terminated by '\t'
stored as textfile;
ALTER TABLE temp_uniontest_tb ADD IF NOT EXISTS PARTITION (dt = '2014-10-13') location '/temp/unionTest/tb/';
d1 d2 2014-10-13
e1 e2 2014-10-13
select * from
(
select a1,a2 from temp_uniontest_ta where dt = '2014-10-13'
union all
select a1,a2 from temp_uniontest_tb where dt = '2014-10-13'
)tmp;
a1 a2
b1 b2
c1 c2
d1 d2
e1 e2
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