Hive面试题:multi group by的好处,举例说明

multi group by 能够将查询中的多个group by操做组装到一个MapReduce任务中,起到优化做用优化 例子:ci select Provice,city,county,count(rainfall) from area where data="2018-09-02" group by provice,city,countit select Provice,count(rainf
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