Andrew Palumbo created MAHOUT-1800:
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Summary: 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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