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https://issues.apache.org/jira/browse/ARROW-14805?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Joris Van den Bossche updated ARROW-14805:
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Summary: [C++][Dataset] Support Count function without projections in ORC
to avoid loading all columns (was: [C++] Support Count function without
projections in ORC to avoid loading all columns)
> [C++][Dataset] Support Count function without projections in ORC to avoid
> loading all columns
> ---------------------------------------------------------------------------------------------
>
> Key: ARROW-14805
> URL: https://issues.apache.org/jira/browse/ARROW-14805
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: xiangxiang Shen
> Priority: Major
> Labels: ORC, c++, dataset
>
> For ORC support in dataset, when execute count query without projections,
> just like "select count(*) from table", it will load all columns. Because orc
> lib code is that
> [https://github.com/apache/orc/blob/22828f79a526069d9629719c9476b7addad91ae6/c%2B%2B/src/Reader.cc#L120-L144.]
>
> Arrow side can improve it like parquet in dataset.
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