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Posted to jira@arrow.apache.org by "xiangxiang Shen (Jira)" <ji...@apache.org> on 2021/11/24 08:32:00 UTC

[jira] [Created] (ARROW-14805) [C++] Support Count function without projections to avoid loading all columns

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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