[jira] [Commented] (HBASE-26340) TableSplit returns false size under 1MB

["Norbert Kalmár (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-26340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17426084#comment-17426084 ] 

Norbert Kalmár commented on HBASE-26340:
----------------------------------------

Although I guess this is improvement from mapred1 package's implementation:


{code:java}
public long getLength() {
    // Not clear how to obtain this... seems to be used only for sorting splits
    return 0;
  }
{code}


> TableSplit returns false size under 1MB
> ---------------------------------------
>
>                 Key: HBASE-26340
>                 URL: https://issues.apache.org/jira/browse/HBASE-26340
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Norbert Kalmár
>            Assignee: Norbert Kalmár
>            Priority: Major
>
> We calculate region size in the mapreduce package by getting the size in MB first and multiplying: https://github.com/apache/hbase/blob/39a20c528e2bf27cedf12734dbdb1b7b1e538076/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/RegionSizeCalculator.java#L87
> This will give a size of 0 until at least 1MB is reached. (And it will have an unwanted rounding affect as well). 
> Spark for example can be tuned to do some performance tuning by eliminating the 0 sized regions. This will eliminate any small regions which are not actually empty. The hadoop interface states the size is returned in bytes, and while this is true do to the multiplication, we multiply by 0 until 1MB is reached. I'm not sure why we get the size in MB units and not in bytes straight up.



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