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Posted to issues@arrow.apache.org by "Ben Kietzman (Jira)" <ji...@apache.org> on 2020/02/21 18:10:00 UTC

[jira] [Created] (ARROW-7916) [C++][Dataset] Project IPC record batches to materialized fields

Ben Kietzman created ARROW-7916:
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             Summary: [C++][Dataset] Project IPC record batches to materialized fields
                 Key: ARROW-7916
                 URL: https://issues.apache.org/jira/browse/ARROW-7916
             Project: Apache Arrow
          Issue Type: Improvement
          Components: C++, C++ - Dataset
    Affects Versions: 0.16.0
            Reporter: Ben Kietzman
            Assignee: Ben Kietzman
             Fix For: 1.0.0


If batches mmaped from disk are projected before post filtering, unreferenced columns will never be accessed (so the memory map shouldn't do I/O on them).

At the same time, it'd probably be wise to explicitly document that batches yielded directly from fragments rather than from a Scanner will not be filtered or projected (so they will not match the fragment's schema and will include columns referenced by the filter even if they were not projected).



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