[jira] [Commented] (ARROW-1712) [C++] Add method to BinaryBuilder to reserve space for value data

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-1712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16327454#comment-16327454 ] 

ASF GitHub Bot commented on ARROW-1712:
---------------------------------------

wesm commented on issue #1481: ARROW-1712: [C++] Add method to BinaryBuilder to reserve space for value data
URL: https://github.com/apache/arrow/pull/1481#issuecomment-358045671
 
 
   @xuepanchen thank you for your contribution. We need to add a new method to `BinaryBuilder` for this use case. 
   
   To give an example, suppose that we anticipate building an array with 1000 elements, each of which has an expected size of around 100 bytes. You would want to write something like:
   
   ```
   RETURN_NOT_OK(builder.Reserve(1000));
   RETURN_NOT_OK(builder.ReserveData(100 * 1000));
   ```
   
   (@xhochy do you have an opinion on what to call this?)
   
   Please also add a method to return the capacity of the internal `value_data_builder_` and add unit tests to `array-test.cc`. Thanks!

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


> [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



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)