[jira] [Commented] (DRILL-5709) Provide a value vector method to convert a vector to nullable

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

    [ https://issues.apache.org/jira/browse/DRILL-5709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16120782#comment-16120782 ] 

ASF GitHub Bot commented on DRILL-5709:
---------------------------------------

GitHub user paul-rogers opened a pull request:

    https://github.com/apache/drill/pull/901

    DRILL-5709: Provide a value vector method to convert a vector to nullable

    Please see the DRILL-5709 for an explanation and example.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/paul-rogers/drill DRILL-5709

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/drill/pull/901.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #901
    
----
commit ced37d52d161daae333d6048150f92c181defa53
Author: Paul Rogers <pr...@maprtech.com>
Date:   2017-08-09T03:04:24Z

    DRILL-5709: Provide a value vector method to convert a vector to nullable
    
    Please see the DRILL-5709 for an explanation and example.

----


> Provide a value vector method to convert a vector to nullable
> -------------------------------------------------------------
>
>                 Key: DRILL-5709
>                 URL: https://issues.apache.org/jira/browse/DRILL-5709
>             Project: Apache Drill
>          Issue Type: Improvement
>            Reporter: Paul Rogers
>            Assignee: Paul Rogers
>            Priority: Minor
>             Fix For: 1.12.0
>
>
> The hash agg spill work has need to convert a non-null scalar vector to the nullable equivalent. For efficiency, the code wishes to simply transfer the underlying data buffer(s), and create the required "bits" vector, rather than generating code that does the transfer row-by-row.
> The solution is to add a {{toNullable(ValueVector nullableVector)}} method to the {{ValueVector}} class, then implement it where needed.
> Since the target code only works with scalars (that is, no arrays, no maps, no lists), the code only handles these cases, throwing an {{UnsupportedOperationException}} in other cases.
> Usage:
> {code}
> ValueVector nonNullableVector = // your non-nullable vector
> MajorType type = MajorType.newBuilder(nonNullableVector.getType)
>     .setMode(DataMode.OPTIONAL)
>     .build();
> MaterializedField field = MaterializedField.create(name, type);
> ValueVector nullableVector = TypeHelper.getNewVector(field, oContext.getAllocator());
> nonNullableVector.toNullable(nullableVector);
> // Data is now in nullableVector
> {code}



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