hive优化之自动合并输出的小文件

<property>
 <name>hive.merge.smallfiles.avgsize</name>
 <value>536870912</value>
 <description>When the average output file size of a job is less than this number, Hive will start an additional map-reduce job to merge the output files into bigger files. This is only done for map-only jobs if hive.merge.mapfiles is true, and for map-reduce jobs if hive.merge.mapredfiles is true.</description>
</property>

<property>
 <name>hive.merge.mapfiles</name>
 <value>true</value>
 <description>Merge small files at the end of a map-only job</description>
</property>

<property>
 <name>hive.merge.mapredfiles</name>
 <value>true</value>
 <description>Merge small files at the end of a map-reduce job</description>
</property>