```rust
use appwrite::Client;
use appwrite::services::Postgresql;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
let client = Client::new();
client.set_endpoint("https://<REGION>.cloud.appwrite.io/v1"); // Your API Endpoint
client.set_project("<YOUR_PROJECT_ID>"); // Your project ID
client.set_key("<YOUR_API_KEY>"); // Your secret API key
let postgresql = Postgresql::new(&client);
let result = postgresql.update_backup_storage(
"<DATABASE_ID>",
"s3",
"<BUCKET>",
"<ACCESS_KEY>",
"<SECRET_KEY>",
Some("<REGION>"), // optional
Some("<PREFIX>"), // optional
Some("<ENDPOINT>") // optional
).await?;
let _ = result;
Ok(())
}
```