摘要:
先说结论,两者没有区别,先看执行计划 1、group by explain select prov_id from dim.dim_city group by prov_id ; STAGE DEPENDENCIES: Stage-1 is a root stage Stage-0 depends 阅读全文
摘要:
对于简单的hivesql,看懂执行计划能细致的知道怎么优化 对于如下这一段简单的sql,看下explain出来的内容 select prov_id ,deep ,count(1) as num from dim.dim_city where prov_id = 110000 and deep = 1 阅读全文