Presto - using serde on lists?

Question

I have a JSON-file with contents like this:

{
  "key1": [
    "value1"
  ],
  "key2": [
    {
      "key3": "value3",
      "key4": "value4
    }
  ],
  "key5": "value5"
}

To create a serde-table in presto for this file (without "key1") I would do:

create table table_one
(
  key2 ARRAY (
    ROW (
      key3 varchar,
      key4 varchar
    )
  ),
  key5 varchar
)...

Which works fine. But my problem is how can I get the attribute "key1" displayed in the serde table as well when it doesn't have a key-value inside the [] in the JSON-file?

Thanks, Bjørn

Answer 1

You can just define it straight away as array of varchar, assuming it's a list of strings.

create table table_two
(
  key1 ARRAY (varchar),
  key2 ARRAY (
    ROW (
      key3 varchar,
      key4 varchar
    )
  ),
  key5 varchar
);