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https://issues.apache.org/jira/browse/SYSTEMML-2173?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matthias Boehm closed SYSTEMML-2173.
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Resolution: Fixed
Assignee: Matthias Boehm
Fix Version/s: SystemML 1.1
> Upper bound nnz propagation over spark instructions
> ---------------------------------------------------
>
> Key: SYSTEMML-2173
> URL: https://issues.apache.org/jira/browse/SYSTEMML-2173
> Project: SystemML
> Issue Type: Sub-task
> Reporter: Matthias Boehm
> Assignee: Matthias Boehm
> Priority: Major
> Fix For: SystemML 1.1
>
>
> Due to lazy evaluation, many spark instructions propagate nnz only if they
> can be exactly inferred from the input meta data. Especially for ultra-sparse
> matrices this poses a challenge because intermediates quickly reach a state
> where they're assumed to be dense. However, many operations such as right
> indexing allow to upper bound the nnz with the nnz in the input, which can be
> propagated and exploited in subsequent instructions.
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