[jira] [Commented] (DRILL-5657) Implement size-aware result set loader

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

    [ https://issues.apache.org/jira/browse/DRILL-5657?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16100473#comment-16100473 ] 

ASF GitHub Bot commented on DRILL-5657:
---------------------------------------

Github user paul-rogers commented on the issue:

    https://github.com/apache/drill/pull/866
  
    Let's defer this one so we can focus on the lower layer: the column accessors for maps and lists (DRILL-5688). Once that PR is done, we'll come back and update this one with those revisions. Please continue to get familiar with the concepts here. However, the details will change a bit to allow support for repeated maps and lists.


> Implement size-aware result set loader
> --------------------------------------
>
>                 Key: DRILL-5657
>                 URL: https://issues.apache.org/jira/browse/DRILL-5657
>             Project: Apache Drill
>          Issue Type: Improvement
>    Affects Versions: Future
>            Reporter: Paul Rogers
>            Assignee: Paul Rogers
>             Fix For: Future
>
>
> A recent extension to Drill's set of test tools created a "row set" abstraction to allow us to create, and verify, record batches with very few lines of code. Part of this work involved creating a set of "column accessors" in the vector subsystem. Column readers provide a uniform API to obtain data from columns (vectors), while column writers provide a uniform writing interface.
> DRILL-5211 discusses a set of changes to limit value vectors to 16 MB in size (to avoid memory fragmentation due to Drill's two memory allocators.) The column accessors have proven to be so useful that they will be the basis for the new, size-aware writers used by Drill's record readers.
> A step in that direction is to retrofit the column writers to use the size-aware {{setScalar()}} and {{setArray()}} methods introduced in DRILL-5517.
> Since the test framework row set classes are (at present) the only consumer of the accessors, those classes must also be updated with the changes.
> This then allows us to add a new "row mutator" class that handles size-aware vector writing, including the case in which a vector fills in the middle of a row.



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