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https://issues.apache.org/jira/browse/DRILL-7096?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16914394#comment-16914394
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ASF GitHub Bot commented on DRILL-7096:
---------------------------------------

vvysotskyi commented on pull request #1829: DRILL-7096: Develop vector for 
canonical Map<K,V>
URL: https://github.com/apache/drill/pull/1829#discussion_r317151040
 
 

 ##########
 File path: 
exec/java-exec/src/main/java/org/apache/drill/exec/record/TypedFieldId.java
 ##########
 @@ -42,6 +45,7 @@
   final boolean isHyperReader;
   final boolean isListVector;
   final PathSegment remainder;
+  private final Map<Integer, MajorType> types;
 
 Review comment:
   Could you please add a comment that this field is used to determine that the 
map is placed at a specific depth. Also, would it be simpler to use `BitSet` 
instead of `Map<Integer, MajorType>` for these purposes?
 
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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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