Are external tables read-only, meaning no DML operations can be performed?

• A. True
• B. False
• C. Some DML allowed
• D. Only INSERT allowed

Answer: (A)

External tables read data from an external location (like S3 or Azure Blob) and Snowflake does not own those files. Because the data isn’t stored in Snowflake, you can only run read operations against the external table. DML operations—such as inserting, updating, or deleting data—aren’t supported on an external table.

If you need to change or transform the data, you’d either modify the source data and reload, or bring the data into Snowflake as an internal table (for example, using a CREATE TABLE AS SELECT or loading from the external stage into a Snowflake table). Once the data lives in a Snowflake table, you can apply DML as needed.