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Posted to jira@arrow.apache.org by "Ben Kietzman (Jira)" <ji...@apache.org> on 2021/02/16 18:39:00 UTC

[jira] [Created] (ARROW-11647) [C++][Compute] CastFromNull does not use preallocated buffers

Ben Kietzman created ARROW-11647:
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             Summary: [C++][Compute] CastFromNull does not use preallocated buffers
                 Key: ARROW-11647
                 URL: https://issues.apache.org/jira/browse/ARROW-11647
             Project: Apache Arrow
          Issue Type: Improvement
          Components: C++
            Reporter: Ben Kietzman
            Assignee: Ben Kietzman
             Fix For: 4.0.0


When casting from null, currently new buffers are allocated for every batch of the computation. This is wasteful as for simple types data buffers are preallocated and the null bitmap is handled separately; CastFromNull need do no work at all (unless we decide to explicitly zero the data buffer). For varlength out types the offsets buffer is preallocated and should be zeroed, for struct types preallocation is not implemented (but should be as simple as preallocating each child array).



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