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https://issues.apache.org/jira/browse/DRILL-7096?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16894570#comment-16894570
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ASF GitHub Bot commented on DRILL-7096:
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paul-rogers commented on issue #1829: DRILL-7096: Develop vector for canonical
Map<K,V>
URL: https://github.com/apache/drill/pull/1829#issuecomment-515716369
Looks like lots of work went into adapting the old-school complex readers
and writers for this new type, but the newer column readers and writers don't
have support. As a result, folks who want to use this feature need to use the
old-style readers; the newer style "EVF" won't be usable for true maps.
While undoubtedly this implementation is exactly what one particular use
case needs; I do wonder at the wisdom of creating pools of partially supported
features that reflect which sponsor pays for the work.
Said another way, it would be very helpful, to encourage folks to create new
readers, if the true map PR included EVF support.
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> Develop vector for canonical Map<K,V>
> -------------------------------------
>
> Key: DRILL-7096
> URL: https://issues.apache.org/jira/browse/DRILL-7096
> Project: Apache Drill
> Issue Type: Sub-task
> Reporter: Igor Guzenko
> Assignee: Bohdan Kazydub
> Priority: Major
> Fix For: 1.17.0
>
>
> Canonical Map<K,V> datatype can be represented using combination of three
> value vectors:
> keysVector - vector for storing keys of each map
> valuesVector - vector for storing values of each map
> offsetsVector - vector for storing of start indexes of next each map
> So it's not very hard to create such Map vector, but there is a major issue
> with such map representation. It's hard to search maps values by key in such
> vector, need to investigate some advanced techniques to make such search
> efficient. Or find other more suitable options to represent map datatype in
> world of vectors.
> After question about maps, Apache Arrow developers responded that for Java
> they don't have real Map vector, for now they just have logical Map type
> definition where they define Map like: List< Struct<key:key_type,
> value:value_type> >. So implementation of value vector would be useful for
> Arrow too.
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