hive中设置查询不启动mapreduce作业（默认不启动）hive-site.xml关键配置

    hive.fetch.task.conversion

    more

   

      Expects one of [none, minimal, more].

      Some select queries can be converted to single FETCH task minimizing latency.

      Currently the query should be single sourced not having any subquery and should not have

      any aggregations or distincts (which incurs RS), lateral views and joins.

      0. none : disable hive.fetch.task.conversion

      1. minimal : SELECT STAR, FILTER on partition columns, LIMIT only

      2. more    : SELECT, FILTER, LIMIT only (support TABLESAMPLE and virtual columns)