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Posted to issues@systemml.apache.org by "Deron Eriksson (JIRA)" <ji...@apache.org> on 2016/09/12 16:54:21 UTC
[jira] [Commented] (SYSTEMML-906) Use of `df.first` in
MLContextUtil is a Bottleneck
[ https://issues.apache.org/jira/browse/SYSTEMML-906?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15484613#comment-15484613 ]
Deron Eriksson commented on SYSTEMML-906:
-----------------------------------------
An potential issue with using the schema is that if a value in a dataframe is a double but is represented as a DataTypes.StringType, then it won't be recognized correctly.
Is there a dataframe method that can grab any row rather than the first row that doesn't cause a bottleneck?
> Use of `df.first` in MLContextUtil is a Bottleneck
> --------------------------------------------------
>
> Key: SYSTEMML-906
> URL: https://issues.apache.org/jira/browse/SYSTEMML-906
> Project: SystemML
> Issue Type: Improvement
> Reporter: Mike Dusenberry
>
> The use of {{dataframe.first()}} at {{MLContextUtil.java:497}} causes a severe bottleneck if the input DataFrame is a lazy result of a compute-intensive chain. We should change this to use {{dataframe.schema}}, and then iterate over the types in the schema.
> cc [~deron]
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