You’ve recently spent several days importing data from CSV files into a BigQuery table named CLICK_STREAM_LOGS for SkyMart Corp. The table includes a column named dt , which currently stores click event timestamps in epoch format as strings. For simplicity, you originally defined all fields as STRING data types. Now, you need to calculate web session durations based on these click events, and you want to convert dt to the TIMESTAMP type. Your goal is to keep the migration process as minimal as possible while ensuring future queries remain efficient. What should you do?