[jira] [Commented] (ARROW-7945) [C++][Dataset] Implement InMemoryDatasetFactory

["Niklas B (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-7945?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17139962#comment-17139962 ] 

Niklas B commented on ARROW-7945:
---------------------------------

Would this also make us able (in the end) to create a dataset from a RecordBatch or Table? Specifically: 
{noformat}
    # TODO(kszucs): support InMemoryDataset for a table input
{noformat}
From [https://github.com/apache/arrow/blob/master/python/pyarrow/dataset.py#L660]

That would be awesome :) that would (if my understand is correct) open up for using filtering on Table/RecordBatch similar to what you can do with the new dataset API for parquet files, but for in memory datasets. 

> [C++][Dataset] Implement InMemoryDatasetFactory
> -----------------------------------------------
>
>                 Key: ARROW-7945
>                 URL: https://issues.apache.org/jira/browse/ARROW-7945
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: C++
>    Affects Versions: 0.16.0
>            Reporter: Ben Kietzman
>            Assignee: Ben Kietzman
>            Priority: Major
>              Labels: dataset
>
> This will allow in memory datasets (such as tables) to participate in discovery through {{UnionDatasetFactory}}. This class will be trivial since Inspect will do nothing but return the table's schema, but is necessary to ensure that the resulting {{UnionDataset}}'s unified schema accommodates the table's schema (for example including fields present only in the table's schema or emitting an error when unification is not possible)



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