[GitHub] [arrow-datafusion] lightjacket commented on issue #1604: Set-returning UDFs

[GitBox <gi...@apache.org>]

lightjacket commented on issue #1604:
URL: https://github.com/apache/arrow-datafusion/issues/1604#issuecomment-1015521579


   @Jimexist thanks for the suggestion! I did consider that as an alternative but would need to `unnest` the result in order to be able to join against additional tables like so:
   Set-returning
   ```sql
   SELECT * FROM 
   (SELECT inverted_index_search('some query') as item_id) t
   LEFT JOIN additional_data ON t.item_id = additional_data.item_id;
   ```
   Single row w/ a list
   ```sql
   SELECT * FROM 
   (SELECT unnest(inverted_index_search('some query')) as item_id) t
   LEFT JOIN additional_data ON t.item_id = additional_data.item_id;
   ```
   So if the `unnest` function existed, I would be unblocked. I _think_ if I could create a set-returning UDF I could also implement `unnest` myself as a user and wouldn't need to wait on a built-in `unnest`.
   
   If there is an alternative to `unnest` to get that join I am looking for though, that would absolutely work. I just haven't found it yet if it exists.


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