could not find array type for data type character varying[]

Hi,

I'm trying to aggregate a list of table attributes into an array.

The actual code looks something like this:

SELECT
node_ref AS id,
array_agg(DISTINCT ARRAY[namespace, name, value]) as annotations
...
GROUP BY id;

I guess the minimal example that reproduces the error is:

annis=> select array_agg(array['a'::varchar, 'b', 'c']);
ERROR: could not find array type for data type character varying[]

Why doesn't this work?

Cheers,
Viktor