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https://issues.apache.org/jira/browse/DRILL-6585?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16546014#comment-16546014
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ASF GitHub Bot commented on DRILL-6585:
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paul-rogers commented on issue #1367: DRILL-6585: PartitionSender clones
vectors, but shares field metdata
URL: https://github.com/apache/drill/pull/1367#issuecomment-405457988
@sohami, the problem is simply that each value vector can stand alone: the
`values` vector is, itself, a perfectly valid vector. However, the
`MaterializedField` metadata for the `values` vector is inconsistent with the
vector class. I considered this a bug. But, given the hassle with this PR, we
may want to declare that inconsistency a feature.
In the result set loader code, I tried to use the vector metadata to
recursively manage vectors: a required int vector (say) was to be handled the
same whether it is a "top-level" or nested `values` vector. The result was
nice, simple code.
I will instead revise the code use the class of the vector as accurate
metadata, and not rely on the unreliable metadata.
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> PartitionSender clones vectors, but shares field metdata
> --------------------------------------------------------
>
> Key: DRILL-6585
> URL: https://issues.apache.org/jira/browse/DRILL-6585
> Project: Apache Drill
> Issue Type: Bug
> Affects Versions: 1.13.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Priority: Major
>
> See the discussion for [PR #1244 for
> DRILL-6373|https://github.com/apache/drill/pull/1244].
> The PartitionSender clones vectors. But, it does so by reusing the
> {{MaterializedField}} from the original vector. Though the original authors
> of {{MaterializedField}} apparently meant it to be immutable, later changes
> for maps and unions ended up changing it to add members.
> When cloning a map, we get the original map materialized field, then start
> doctoring it up as we add the cloned map members. This screws up the original
> map vector's metadata.
> The solution is to clone an empty version of the materialized field when
> creating a new vector.
> But, since much code creates vectors by giving a perfectly valid, unique
> materialized field, we want to add a new method for use by the ill-behaved
> uses, such as PartitionSender, that ask to create a new vector without
> cloning the materialized field.
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