From : http://religiose.iteye.com/blog/1685537
一,如何判断SQL的执行效率?
通过explain 关键字分析效率低的SQL执行计划。
比如: explain select sum(moneys) from sales a, company b where a.company...
执行语句
hive> explain select s.id, s.name from student s left outer join student_tmp st on s.name = st.name;
结果,红色字体为我添加的注释
hive> explain select s.id, s.name from student s lef...