Hive优化(十六)-使用EXPLAIN（执行计划）

1）基本语法
EXPLAIN [EXTENDED | DEPENDENCY | AUTHORIZATION] query

2）案例实操
（1）查看下面这条语句的执行计划

hive (default)> explain select * from course;
hive (default)> explain select s_id ,avg(s_score) avgscore from score group by s_id;

（2）查看详细执行计划

hive (default)> explain extended select * from course;
hive (default)> explain extended select s_id ,avg(s_score) avgscore from score group by s_id;