Source Taste: JPA: InheritanceType

package javax.persistence;

/**
 * Defines inheritance strategy options.
 *
 * @since Java Persistence 1.0
 */
public enum InheritanceType {

    /** A single table per class hierarchy. */
    SINGLE_TABLE,

    /** A table per concrete entity class. */
    TABLE_PER_CLASS,

    /**
     * A strategy in which fields that are specific to a
     * subclass are mapped to a separate table than the fields
     * that are common to the parent class, and a join is
     * performed to instantiate the subclass.
     */
    JOINED
}

Quoted from <Java Persistence with Hibernate>: This mapping strategy (SINGLE_TABLE) is a winner in terms of both performance and simplicity. It's the best-performing way to represent polymorphism--both polymorphic and nonpolymorphic queries perform well--and it's even easy to implement by hand. Ad-hoc reporting is possible without complex joins or unions. Schema evolution is straightforward.