Dandandan opened a new pull request #9937:
URL: https://github.com/apache/arrow/pull/9937


   This PR adds a (ignored) test for 
https://issues.apache.org/jira/browse/ARROW-12266
   
   ```
   SELECT id1, id2 FROM (SELECT null AS id1) t1
   LEFT JOIN (SELECT 0 AS id2) t2 ON id1 = id2
   ```
   
   current result:
   
   ```NULL, NULL```
   
   (should be empty result set)
   
   We should filter on nulls beforehand to make this result correct. Probably 
the best way to go here I think is to add a filter in the logical plan on 
non-null for inner / left and right joins.
   This can make things more efficient as the non-null filter can be pushed 
down which can lead to efficiency gains (making data-set smaller, not having to 
deal with nullable data in batches, or even entire files could be skipped when 
they only contain nulls).
   
   
   


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