xiangxiang Shen created ARROW-14805:
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Summary: [C++] Support Count function without projections 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
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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