[
https://issues.apache.org/jira/browse/ARROW-5336?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17252084#comment-17252084
]
Weston Pace commented on ARROW-5336:
------------------------------------
So the unifier currently reassigns the index type to be as small as needed.
Pros:
* Allows unification of arrays that don't have the same index type
* Resulting dictionary will be as space efficient as possible
Cons:
* Combining arrays could modify the type of the array
* We don't tolerate differences in other types (e.g. we can't combine int8()
with int16())
Right now I'm planning on disabling this for concatenate. All incoming arrays
must have identical value and index types and the resulting array will have the
same value and index type. I will leave the capability in the unifier but
allow for an index type to be specified that will override the auto-calculate.
> [C++] Implement arrow::Concatenate for dictionary-encoded arrays with unequal
> dictionaries
> ------------------------------------------------------------------------------------------
>
> Key: ARROW-5336
> URL: https://issues.apache.org/jira/browse/ARROW-5336
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Wes McKinney
> Assignee: Weston Pace
> Priority: Major
> Fix For: 3.0.0
>
>
> Currently (as of ARROW-3144) if any dictionary is different, an error is
> returned
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
