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https://issues.apache.org/jira/browse/ARROW-16616?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17557545#comment-17557545
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Alessandro Molina commented on ARROW-16616:
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I'm not fond of relying on {{Scanner}} because it looks like violating the
single responsibility principle as it would have to grow nearly the same
capabilities of {{Dataset}} (for example if I want to do a join over filtered
data, we would have to implement {{Scanner.join}} which doesn't seem to make
much sense).
Another direction I thought about was going toward having a {{FilteredDataset}}
class, that would still inherit from {{Dataset}} but clearly provide a
separation of concerns.
> [Python] Allow lazy evaluation of filters in Dataset and add Datset.filter
> method
> ---------------------------------------------------------------------------------
>
> Key: ARROW-16616
> URL: https://issues.apache.org/jira/browse/ARROW-16616
> Project: Apache Arrow
> Issue Type: Sub-task
> Components: Python
> Reporter: Alessandro Molina
> Priority: Major
> Labels: pull-request-available
> Fix For: 9.0.0
>
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> To keep the {{Dataset}} api compatible with the {{Table}} one in terms of
> analytics capabilities, we should add a {{Dataset.filter}} method. The
> initial POC was based on {{_table_filter}} but that required materialising
> all the {{Dataset}} content after filtering as it returned an
> {{{}InMemoryDataset{}}}.
> Given that {{Scanner}} can filter a dataset without actually materialising
> the data until a final step happens, it would be good to have
> {{Dataset.filter}} return some form of lazy dataset when the filter is only
> stored aside and the Scanner is created when data is actually retrieved.
> PS: Also update {{test_dataset_filter}} test to use the {{Dataset.filter}}
> method
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