Making RCFile "concatenatable" to reduce the number of files of the output
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Key: HIVE-1071
URL: https://issues.apache.org/jira/browse/HIVE-1071
Project: Hadoop Hive
Issue Type: Improvement
Reporter: Zheng Shao
Hive automatically determine the number of reducers most of the time.
Sometimes, we create a lot of small files.
Hive has an option to "merge" those small files though a map-reduce job.
Dhruba has the idea which can fix it even faster:
if we can make RCFile concatenatable, then we can simply tell the namenode to
"merge" these files.
Pros: This approach does not do any I/O so it's faster.
Cons: We have to zero-fill the files to make sure they can be concatenated (all
blocks except the last have to be full HDFS blocks).
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