Presto map(varchar,varchar) : How to get all the possible keys for it?

Question

I am trying to search a column having the data type map(varchar,varchar). Now one way to access the column is to use this structure, name_of_column['key'], which will give the value for that key. But I want to know what are possible keys and then apply group by and other operations based on those keys.

I tried searching on the internet but was not able to find appropriate solution.

Piotr Findeisen · Accepted Answer · 2019-02-01T17:53:34.467

9

Presto offers map_keys function for that:

presto> select map_keys(map(array['alice'], array['has a cat']));
  _col0
---------
 [alice]
(1 row)

edited Feb 01 '19 at 17:53

answered Jul 14 '17 at 09:05

Piotr Findeisen

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4

This returns an array of the keys for each row. How can I combine all the results as its own column? – eriel marimon Feb 07 '21 at 07:49

Presto map(varchar,varchar) : How to get all the possible keys for it?

1 Answers1