优雅的HiveQL查询

Question

我有一个文件，其中的行如下：

232404812.913232|1248|ip:tcp:jxta
232404812.913238|66|ip:udp:data
232404812.913615|98|ip:udp:l2tp:ppp:ip:tcp

我执行了以下HiveQL命令：

CREATE EXTERNAL TABLE b_packet (timestamp string, packet_length int, protocol string) 
ROW FORMAT DELIMITED FIELDS TERMINATED BY "|" 
LOCATION 's3://b-file/input/'; 
CREATE EXTERNAL TABLE b_packet_out (protocol string, cnt int) 
ROW FORMAT DELIMITED FIELDS TERMINATED BY "t" 
LOCATION 's3://b-file/output/1/'; 
INSERT OVERWRITE TABLE b_packet_out SELECT 'overall', 
COUNT(*) FROM b_packet GROUP BY protocol; 
INSERT INTO TABLE b_packet_out SELECT 'tcp', 
COUNT(*) FROM b_packet WHERE protocol REGEXP '^ip:tcp'; 
INSERT INTO TABLE b_packet_out SELECT 'udp', 
COUNT(*) FROM b_packet WHERE protocol REGEXP '^ip:udp'; 
INSERT INTO TABLE b_packet_out SELECT 'icmp', 
COUNT(*) FROM b_packet WHERE protocol REGEXP '^ip:icmp'; 

因此，我在输出表中有以下内容。

hive> select * from b_packet_out;
OK
udp 2241
overall 10000
icmp    64
tcp 7633

对于HiveQL查询，有没有更优雅的方法可以减少行数以获得相同的输出？

Answer 1

select 
count(*) as overall,
sum( if(protocol like '^ip:tcp',1,0) as tcp,
sum( if(protocol like '^ip:udp',1.0) as udp,
sum( if(protocol like '^ip:icmp'1,0) as icmp 
from b_packet  

这将通过一次数据传递生成相同的计数。

如果你有更多的协议，你也可以说选择split（协议，"："）[1]，计数（*）按拆分分组（协议，"："）[1]但这并不能给出总数。

Answer 2

这里有一个不同的解决方案，但它对数据进行多次传递，并不会真正节省代码行的数量：

SELECT          CASE WHEN GROUPING__ID = 0 THEN 'overall' ELSE 
                        CASE WHEN protocol LIKE 'ip:tcp%' THEN 'tcp'
                             WHEN protocol LIKE 'ip:udp%' THEN 'udp'
                             WHEN protocol LIKE 'ip:icmp%' THEN 'icmp'   END  END    AS protocol 
                , COUNT(1)                                                           AS cnt 
FROM            b_packet  
GROUP BY        CASE WHEN protocol LIKE 'ip:tcp%' THEN 'tcp'
                     WHEN protocole LIKE 'ip:udp%' THEN 'udp'
                     WHEN protocol LIKE 'ip:icmp%' THEN 'icmp'   END
GROUPING SETS   (
                    (CASE WHEN protocol LIKE 'ip:tcp%' THEN 'tcp'
                          WHEN protocol LIKE 'ip:udp%' THEN 'udp'
                          WHEN protocol LIKE 'ip:icmp%' THEN 'icmp'  END)
                    , () 
                )