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https://issues.apache.org/jira/browse/ARROW-1712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16332613#comment-16332613
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ASF GitHub Bot commented on ARROW-1712:
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wesm commented on a change in pull request #1481: ARROW-1712: [C++] Add method
to BinaryBuilder to reserve space for value data
URL: https://github.com/apache/arrow/pull/1481#discussion_r162686328
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File path: cpp/src/arrow/builder.h
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@@ -682,10 +682,13 @@ class ARROW_EXPORT BinaryBuilder : public ArrayBuilder {
Status Init(int64_t elements) override;
Status Resize(int64_t capacity) override;
+ Status ReserveData(int64_t capacity);
Review comment:
Can you add a doxygen comment, since this is a new API
I note that the `Reserve`-type methods in this header have different
semantics from their STL counterparts. They are reserving _additional_ space
rather than _absolute_ space (e.g. std::vector::reserve takes an absolute
length as argument)
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> [C++] Add method to BinaryBuilder to reserve space for value data
> -----------------------------------------------------------------
>
> Key: ARROW-1712
> URL: https://issues.apache.org/jira/browse/ARROW-1712
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Wes McKinney
> Assignee: Panchen Xue
> Priority: Major
> Labels: pull-request-available
> Fix For: 0.9.0
>
>
> The {{Resize}} and {{Reserve}} methods only reserve space for the value
> offsets. When building binary/string arrays with a known size (or some
> reasonable estimate), it would be more efficient to reserve once at the
> beginning to prevent internal reallocations
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