Can a scenario be ignored? In the next scenario, how do you identify and update changes?

To identify changes you rely on the stream’s metadata columns. METADATA$ACTION tells you whether the change was an INSERT, UPDATE, or DELETE. METADATA$ROW_ID is a unique identifier for the row. By selecting from the stream and filtering on METADATA$ACTION you can separate new, changed, and removed rows. Once identified, you can apply them to a target table using a MERGE or separate DML statements. If you need to ignore a scenario, simply exclude those rows in your SELECT (e.g., WHERE NOT (condition)). Snowflake streams are incremental, so each read consumes the changes, allowing you to process only the new data.