sql: SELECT DISTINCT jsoncol->foo is broken #24436
Description
Realistic reproduction:
> create table t (ext json);
> insert into t values ('{"foo": "bar"}');
> select distinct ext->'foo' from t;
pq: unable to encode table key: *tree.DJSON
Minimal reproduction:
> select distinct '{}'::json;
pq: unable to encode table key: *tree.DJSON
@justinj suggests that this is because we can't currently key-encode JSON values. As a workaround:
> select distinct ext->>'foo' from t;
+-------------+
| ext->>'foo' |
+-------------+
| bar |
+-------------+
(2 rows)