Annotation Type SortKey

@Retention(CLASS)
@Target(FIELD)
public @interface SortKey

Marks the sort key of a two-column composite identifier, for a document store.

A DynamoDB table is keyed by a partition key and, optionally, a sort key; the items of one partition are stored in sort-key order and read together. An entity says which identifier column is which by marking one of exactly two @Id columns (or two components of an @EmbeddedId) with this annotation; the other is the partition key. MongoDB stores the pair as a compound _id.

@Entity
public class Message {
    @Id(autoIncrement = false) String channel;
    @Id(autoIncrement = false) @SortKey long sentAt;
    String text;
}

A SQL session ignores it: the pair is the table's composite primary key there.