The streaming join will fail because the default join type is an outer join.

Updates to the conversion_rate table will cause an immediate error in the streaming query.

Updates to the conversion_rate table should be made after the current batch is processed and before the next batch arrives.

Updates to the conversion_rate table will cause an error when the next batch of data arrives in the transactions table.

The conversion_rate table should be updated while the join is in progress with a new batch of data.