Constant SELECT_PENDING_SENDS_SQL 

pub const SELECT_PENDING_SENDS_SQL: &str = r#"
SELECT
    checkpoint_id,
    array_agg(array[type::bytea, blob] ORDER BY task_path, task_id, idx) AS sends
FROM checkpoint_writes
WHERE thread_id = $1
    AND checkpoint_id = ANY($2)
    AND channel = '__tasks__'
GROUP BY checkpoint_id
"#;

Select pending sends for migration.