Use block-level merge for RCFile if merging intermediate results are needed
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Key: HIVE-2035
URL: https://issues.apache.org/jira/browse/HIVE-2035
Project: Hive
Issue Type: Improvement
Reporter: Ning Zhang
Assignee: He Yongqiang
Currently if hive.merge.mapredfiles and/or hive.merge.mapfile is set to true
the intermediate data could be merged using an additional MapReduce job. This
could be quite expensive if the data size is large. With HIVE-1950, merging can
be done in the RCFile block level so that it bypasses the (de-)compression,
(de-)serialization phases. This could improve the merge process significantly.
This JIRA should handle the case where the input table is not stored in RCFile,
but the destination table is (which requires the intermediate data should be
stored in the same format as the destination table).
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