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https://issues.apache.org/jira/browse/DRILL-6585?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16540949#comment-16540949
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ASF GitHub Bot commented on DRILL-6585:
---------------------------------------
vrozov commented on issue #1367: DRILL-6585: PartitionSender clones vectors,
but shares field metdata
URL: https://github.com/apache/drill/pull/1367#issuecomment-404355666
@paul-rogers I am somewhat OK with the code changes granted that they fix
the issue. My concerns are (in random order)
- Usage of the `clone()` where copy constructor should be used (see [Copy
Constructor versus Cloning](https://www.artima.com/intv/bloch13.html))
- Improper implementation of `clone()` by the `MaterializedField`
- Unclear semantics when `MaterializedField` needs to be cloned
- Should not by the time `InitializedBatch` is called, `MaterializedField`
for incoming vectors be fully initialized? If they are, what causes changes in
outgoing vectors `MaterializedField` and if they are not, how changes to
`MaterializedField` in incoming vectors will be propagated to outgoing vectors
`MaterializedField` once they refer to a deep copy?
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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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