1. Risingwave currently has a limitation with using the TUMBLE function with a timestamp within a struct.
2. One workaround is to use a Common Table Expression (CTE) to rename the struct column and then use the renamed column in the TUMBLE function.

-- Example workaround using CTE
with cte as (
  select (s).t as renamed_timestamp, (s).c from t
)
select * from tumble(cte, cte.renamed_timestamp, INTERVAL '60' MINUTE);

3. By renaming the struct column within a CTE, you can use the renamed column in the TUMBLE function without encountering the error.