在工作中用hive进行数据统计的时候,遇到一个用group by 进行查询的问题,需要统计的字段为
gid,sid,user,roleid,time,status,map_id,num
其中time字段为时间戳形式的,统计要求为将各个字段按照每个小时的num总数进行统计
开始的时候写的hive SQL为
select gid,sid,user,roleid,time,status,map_id,sum(num) from test group by gid,sid,user,roleid,from_unixtime(time,'yyyyMMddHHmmss'),9,2),time,status,map_id;
在hive中执行后发现结果不对,hive是按照time字段进行的group by,于是将group by中的time字段去掉
select gid,sid,user,roleid,time,status,map_id,sum(num) from test group by gid,sid,user,roleid,from_unixtime(time,'yyyyMMddHHmmss'),9,2),status,map_id;
hive返回错误FAILED: Error in semantic analysis: Line 1:27 Expression not in GROUP BY key time
如果修改sql为
select gid,sid,user,roleid,from_unixtime(time,'yyyyMMddHHmmss'),9,2),status,map_id,sum(num) from test group by gid,sid,user,roleid,from_unixtime(time,'yyyyMMddHHmmss'),9,2),status,map_id;
可以按照小时进行汇总统计,可是字段time不是想要显示的结果,最后经过google查到方法
select gid,sid,user,roleid,collect_set(time)[0],status,map_id,sum(num) from test group by gid,sid,user,roleid,substr(from_unixtime(time,'yyyyMMddHHmmss'),9,2),status,map_id;
参考网址http://stackoverflow.com/questions/5746687/hive-expression-not-in-group-by-key
看来对hive的udf函数还是掌握的不够,需要多学习
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