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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