Cant Use Grafana API (api/ds/query) with Postgres Backend

Hi guys, I’ve tested grafana dashboard using locust to endpoint api/ds/query, it is working well with 15 concurrent and 10 rps. Because I want to increase the concurrent and rps, I implement postgres backend but now can’t make api call to api/ds/query. Can’t someone explain why I cant make the api call? I can give errors message if necessary.

Regards & thanks!

nevermind, it’s actually me missed the “datasourceId” in json body request