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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2021/04/26 13:24:54 UTC

[GitHub] [arrow-datafusion] alamb commented on issue #130: Implement Value(Null)

alamb commented on issue #130:
URL: https://github.com/apache/arrow-datafusion/issues/130#issuecomment-826832982


   Comment from Mike Seddon(MikeSeddonAU) @ 2020-12-20T01:10:56.266+0000:
   <pre>Added as part of https://github.com/apache/arrow/pull/8966
   
   For future reference:
   
   I have now added the NULL value to both the test cases and the planner.
   
   This is where things get interesting. For this statement:
   
   SELECT NULL
   
   Spark implements a special NullType for this return type but that creates a lot of side effects for things like the Parquet writer and JDBC drivers do not support this type.
   
   I tested Postgres:
   
   CREATE TABLE test AS
   SELECT NULL;
   
   The DDL for this table shows that column as a text type so that is why I have applied the default utf8 type to Value(Null).</pre>


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