What happens to the source table when the first stream for a table is created?

• A. No changes to the table
• B. A pair of hidden columns are added to store change tracking metadata
• C. The table is renamed
• D. It triggers immediate enqueue of CDC data

Answer: (B)

When a stream is created on a table, Snowflake needs a way to track what changed since the last time you read the stream. To do this, it automatically adds two hidden metadata columns to the source table that store change-tracking information. These columns are not visible in normal queries, but they enable the stream to determine which rows were inserted, updated, or deleted and to version or identify each row for the change data it returns. The visible table schema remains the same, and you interact with changes through the stream rather than the table’s ordinary columns. This is why the correct choice notes the addition of hidden change-tracking metadata columns.