Pivoting AWS Redshift SUPER data - sql

Question

I have a following table structure:
server_id
server_databases
1
[{"name": "mssql", "count": 12},{"name": "postgresql", "count": 1}]
2
[]
3
null
What I want to receive as a result(I want to keep servers 2 and 3 if it would be null or empty object doesn't matter):
server_id
databases
1
{"mssql": 12, "postgresql": 1}
2
null
3
null
I've tried to build json myself
SELECT server_id,
(
select '{' || listagg('"' || x.name || '":' || x.count, ',') || '}' as clientdatabases
from (
select cb."name"::varchar as name, sum(cb."count")::int as count from e.server_databases as cb group by name
) x
)
FROM my_table e
But it fails with interestiong error
[XX000] ERROR: Query unsupported due to an internal error. Detail: Unsupported witness case Where: nested_decorrelate_calc_witness_unsupported|calc_witness
It looks like PartiQL supports such cases, but I have no idea how to implement it. I will use UDF for now. But, if you can help me with a "native" solution, it would be amazing.
Update SQL script for case reproduction:
CREATE table my_table(server_id int, server_databases super);
insert into my_table(server_id, server_databases) values (
1, json_parse('[{"name": "mssql", "count": 12},{"name": "postgresql", "count": 1}]')
),
(2, json_parse('[]')),
(3, null);
SELECT server_id,
(
select '{' || listagg('"' || x.name || '":' || x.count, ',') || '}' as clientdatabases
from (
select cb."name"::varchar as name, sum(cb."count")::int as count from e.server_databases as cb group by name
) x
)
FROM my_table e;

Answer 1

Use ISNULL in count :
SELECT server_id,
(
select '{' || listagg('"' || x.name || '":' || x.count, ',') || '}' as clientdatabases
from (
select cb."name"::varchar as name, ISNULL(sum(cb."count")::int,0) as count from e.server_databases as cb group by name
) x
)
FROM my_table e

Answer 2

You can use left join for handling null cases
with b as (select server_id,
('{' || listagg('"' || x.name::text || '":' || x.count::int, ',') || '}') as clientdatabases
from my_table as e, e.server_databases as x
group by server_id)
select a.server_id, a.server_databases, json_parse(b.clientdatabases)
from my_table as a
left join b
on a.server_id = b.server_id;