启用MapReduce Job是会消耗系统开销的.对于这个问题,从Hive0.10.0版本开始,对于简单的不需要聚合的类似SELECT <col> from <table> LIMIT n语句,不需要起MapReduce job,直接通过Fetch task获取数据 set hive.fetch.task.conversion=more; select * from info_table where dt='2017-04-26' limit ;…
如果你想查询某个表的某一列,Hive默认是会启用MapReduce Job来完成这个任务,如下: hive; Total MapReduce jobs Launching Job out since there's no reduce operator Cannot run job locally: Input Size (= 235105473) is larger than hive.exec.mode.local.auto.inputbytes.max (= 134217728) Star…
转自:http://www.iteblog.com/archives/831 如果你想查询某个表的某一列,Hive默认是会启用MapReduce Job来完成这个任务,如下: hive> SELECT ; Total MapReduce jobs = Launching Job out of Number of reduce tasks is set to since there's no reduce operator Cannot run job locally: Input Size (=…
假设你想查询某个表的某一列.Hive默认是会启用MapReduce Job来完毕这个任务,例如以下: 01 hive> SELECT id, money FROM m limit 10; 02 Total MapReduce jobs = 1 03 Launching Job 1 out of 1 04 Number of reduce tasks is set to 0 since there's no reduce operator 05 Cannot run job locally: In…