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https://issues.apache.org/jira/browse/SYSTEMML-1831?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Fei Hu reassigned SYSTEMML-1831:
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Assignee: Fei Hu
> Improve the efficiency of matrix subsetting
> -------------------------------------------
>
> Key: SYSTEMML-1831
> URL: https://issues.apache.org/jira/browse/SYSTEMML-1831
> Project: SystemML
> Issue Type: Improvement
> Reporter: Fei Hu
> Assignee: Fei Hu
>
> For the {{rangeReIndex}} operation, it needs to read the whole input matrix
> into memory first and do the subsetting in the memory. It is not efficient
> because it needs to read a lot of unnecessary data, and even out of memory if
> the size of input matrix exceeds the available memory.
> The plan here is to read the keys in the Hadoop sequence file, and identify
> the keys overlapped with the input range index. Then the values specified by
> the identified keys will be read.
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