Question

A developer needs to ensure that every document written to a Cosmos DB container automatically gets a server-generated 'createdAt' timestamp field, regardless of which client SDK or application performs the insert. The logic must run within Cosmos DB itself before the document is persisted. Which server-side feature should be implemented, and how must it be invoked?

Accepted Answer

A pre-trigger that adds the timestamp; it must be explicitly specified in the request options of each create operation.

Answer

A post-trigger that adds the timestamp; it runs automatically on every insert without client configuration.

Answer

A user-defined function (UDF) that generates the timestamp; it is invoked automatically during document writes.

Answer

A pre-trigger that adds the timestamp; it runs automatically for all writes once registered on the container.