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https://issues.apache.org/jira/browse/MAHOUT-1800?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dmitriy Lyubimov updated MAHOUT-1800:
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Summary: Pare down Casstag overuse (was: Pair down Casstag overuse)
> Pare down Casstag overuse
> -------------------------
>
> Key: MAHOUT-1800
> URL: https://issues.apache.org/jira/browse/MAHOUT-1800
> Project: Mahout
> Issue Type: Improvement
> Affects Versions: 0.11.1
> Reporter: Andrew Palumbo
> Fix For: 0.11.2
>
>
> currently, almost every operator requires implicit parameter for the classtag
> context bound of drm rowset key type, even for things like drmA + drmB.
> in reality though DAG can already infer that similarly to e.g. it infers
> product geometry because classtags are already embedded in the logical plan.
> for example, {{classtag(drmA+drmB) == classtag(drmA) == classtag(drmB)}}.
> Not only does the DAG already contain this information, but also it opens
> doors to a loss of inference, since the optimizer doesn't verify that the new
> context bound is actually valid by retracing the inference. So any operation
> may introduce an invalid row key type, and as a consequence, invalid
> optimization information, without any further checks.
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