Constant UPSERT_CHECKPOINT_WRITES_SQL 

pub const UPSERT_CHECKPOINT_WRITES_SQL: &str = r#"
INSERT INTO checkpoint_writes (thread_id, checkpoint_ns, checkpoint_id, task_id, task_path, idx, channel, type, blob)
VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
ON CONFLICT (thread_id, checkpoint_ns, checkpoint_id, task_id, idx) DO UPDATE SET
    channel = EXCLUDED.channel,
    type = EXCLUDED.type,
    blob = EXCLUDED.blob
"#;

Upsert checkpoint writes (overwrite on conflict).