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Subject [GitHub] [drill] ihuzenko removed a comment on issue #1688: DRILL-7092: Rename map to struct in schema definition
Date Tue, 12 Mar 2019 15:29:26 GMT
ihuzenko removed a comment on issue #1688: DRILL-7092: Rename map to struct in schema definition
URL: https://github.com/apache/drill/pull/1688#issuecomment-472048111
 
 
   > Yes, indeed there has long been a misconception around the use of the type "MAP" in
Drill. It is, indeed, closer to a Hive and Arrow struct. Since it is unclear how would create
a true map using vectors, I suppose that, originally, merging the map and struct concepts
was considered a harmless simplification.
   > 
   > While it is easy to rename the items in this new parser code, it will be far harder
to rename the many existing vectors, metadata elements and so on. Even harder still to rename
to SQL data type itself. Fortunately, it seems that the only place the term "Map" is surfaced
to the user in the code is in the "typeof" set of functions. Up until now, Drill did not have
many DDL statements.
   > 
   > So, the change here LGTM, but I wonder how we plan to roll out the changes to other
parts of the code. Would that be a breaking change for 2.0?
   > 
   > Finally, if this rename is done to prepare for introducing a true map type (collection
of key/value pairs where the set of values is uncorrelated across rows), then is there a design
for that? Would be good to start thinking how that would fit into the new row-set framework
which is heavily based on the current "struct" design.
   > 
   > +1
   
   Hello @paul-rogers , yes both changes (renaming and new MapVector) are in our future plans.
Today I've created two related Jira tickets [DRILL-7097](https://issues.apache.org/jira/browse/DRILL-7097)
and [DRILL-7096](https://issues.apache.org/jira/browse/DRILL-7096) . For now it's pretty raw
ideas, but it would be very good if you can join discussion in jira and share your thoughts
with me and @KazydubB .  

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