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https://issues.apache.org/jira/browse/DRILL-7096?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16894623#comment-16894623
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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-515719706
 
 
   This PR has no unit tests. While I am sure that this particular developer 
got everything 100% correct, I do wonder if future developers might 
accidentally introduce bugs that will only be caught by users in production. 
Without unit tests, we are performing without a safety net. Reviews must 
execute tests in our heads since there is no code to do it for us.
   
   I realize that the consumer of this code really wants this commit in, and 
will worry about tests later. But, as an open source project, it is a good 
practice to require unit tests for all new and changed code.
 
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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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