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Determine the number of map task at most used in the follow up map join job for a skew join by specifying the minimum split size. It should be used together with hive.skewjoin.mapjoin.map.tasks to perform a fine grained control.
hive.optimize.skewjoin.compiletime
- Default Value:
fe - Added In: Hive 0.xxxxxxxxxxxx
The
hive.optimize.union.remove
- Default Value:
false - Added In: Hive 0.10.0 with HIVE-3276
Whether to remove the union and push the operators between union and the filesink above union. This avoids an extra scan of the output by union. This is independently useful for union queries, and especially useful when hive.optimize.skewjoin.compiletime is set to true, since an
extra union is inserted.
The merge is triggered if either of hive.merge.mapfiles or hive.merge.mapredfiles is set to true.
If the user has set hive.merge.mapfiles to true and hive.merge.mapredfiles to false, the idea was the
number of reducers are few, so the number of files anyway are small. However, with this optimization,
we are increasing the number of files possibly by a big margin. So, we merge aggresively.
</property>
hive.mapred.supports.subdirectories
- Default Value:
false - Added In: Hive 0.10.0 with HIVE-3276
The
hive.mapred.mode
- Default Value:
nonstrict - Added In:
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