AWS Athena (Presto) how to transpose map to columns

Question

AWS Athena query question;

I have a nested map in my rows, of which I would like to transpose the keys to columns. I could name the columns explicitly like items[\'

Answer 1

This is not possible in a dynamic manner due to the fact that output columns need to be know to the planner before the query execution starts.

See the previous discussion here: https://github.com/prestosql/presto/issues/2448 and https://github.com/prestosql/presto/issues/1206.