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Posted to issues@arrow.apache.org by "Benjamin Kietzman (JIRA)" <ji...@apache.org> on 2019/06/27 19:10:00 UTC
[jira] [Updated] (ARROW-5760) [C++] Optimize Take and Filter
[ https://issues.apache.org/jira/browse/ARROW-5760?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Benjamin Kietzman updated ARROW-5760:
-------------------------------------
Description:
There is some question of whether these kernels allocate optimally- for example when Filtering or Taking strings it might be more efficient to pass over the filter/indices twice, first to determine how much character storage will be needed then again into allocated memory: https://github.com/apache/arrow/pull/4531#discussion_r297160457
Additionally, these kernels could probably make good use of scatter/gather SIMD instructions.
Furthermore, Filter's bitmap is currently lazily expanded into the indices of elements to be appended to the output array. It would probably be more efficient to expand to indices in batches, then gather using an index batch.
was:
These kernels could probably make good use of scatter/gather SIMD instructions.
Furthermore, Filter's bitmap is currently lazily expanded into the indices of elements to be appended to the output array. It would probably be more efficient to expand to indices in batches, then gather using an index batch.
> [C++] Optimize Take and Filter
> ------------------------------
>
> Key: ARROW-5760
> URL: https://issues.apache.org/jira/browse/ARROW-5760
> Project: Apache Arrow
> Issue Type: New Feature
> Components: C++
> Reporter: Benjamin Kietzman
> Assignee: Benjamin Kietzman
> Priority: Major
>
> There is some question of whether these kernels allocate optimally- for example when Filtering or Taking strings it might be more efficient to pass over the filter/indices twice, first to determine how much character storage will be needed then again into allocated memory: https://github.com/apache/arrow/pull/4531#discussion_r297160457
> Additionally, these kernels could probably make good use of scatter/gather SIMD instructions.
> Furthermore, Filter's bitmap is currently lazily expanded into the indices of elements to be appended to the output array. It would probably be more efficient to expand to indices in batches, then gather using an index batch.
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