1. limit
Hive has a configuration property to enable sampling of source data for use with LIMIT: hive.limit.optimize.enable, set this parameter to true to optimize limit operation. 2. PARALLEL if your job was designed to some stages, if these stages has no dependencies, you can execute them parallel by setting the parameter : set hive.exec.parallel=true; 3. adjust the mapper and reducer task count The default value of hive.exec.reducers.bytes.per.reduceris 1 GB. Changing this value to 750 MB causes Hive to estimate four reducers for this job: hive> set hive.exec.reducers.bytes.per.reducer=750000000;--combinehiveinputformat
set hive.input.format; set mapred.child.java.opts = -Xmx524m; set hive.exec.reducers.bytes.per.reducer=100000000; set hive.merge.size.per.task=10010001000;