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Posted to issues@hbase.apache.org by "Yi Deng (JIRA)" <ji...@apache.org> on 2014/09/05 02:59:23 UTC

[jira] [Created] (HBASE-11900) Optimization for incremental load reducer

Yi Deng created HBASE-11900:
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             Summary: Optimization for incremental load reducer
                 Key: HBASE-11900
                 URL: https://issues.apache.org/jira/browse/HBASE-11900
             Project: HBase
          Issue Type: Improvement
          Components: HFile
    Affects Versions: 0.98.6
            Reporter: Yi Deng
            Priority: Minor


In current implementation, the key of reducer configured by HFileOutputFormat.configureIncrementalLoad, is row. So, the reducer has to do an in-memory sort before writing key values to the disk.  When we meet with some rows with a huge number of comlumns/versions, there could be OOM.

A better way is:
Use the KeyValue as the key, value can be a NullWritable. Partioner partitions the KeyValue only by it's row part. Set a sort comparator that sort KeyValue with KeyValue.COMPARATOR



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