2.6.10. Using identifier table

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Hibernate achieves table-based identifier generation based on its `org.hibernate.id.enhanced.TableGenerator` id generator which defines a table capable of holding multiple named value segments for any number of entities.

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<div class="title">Example 119. Table generator table structure</div>
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<pre class="prettyprint highlight">`create table hibernate_sequences(
    sequence_name VARCHAR NOT NULL,
    next_val INTEGER NOT NULL
)`</pre>
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The basic idea is that a given table-generator table (`hibernate_sequences` for example) can hold multiple segments of identifier generation values.

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<div class="title">Example 120. Unnamed table generator</div>
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<pre class="prettyprint highlight">`@Entity
public class MyEntity {

    @Id
    @GeneratedValue( generation = TABLE )
    public Integer id;

    ...
}`</pre>
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If no table name is given Hibernate assumes an implicit name of `hibernate_sequences`.
Additionally, because no `javax.persistence.TableGenerator#pkColumnValue` is specified, Hibernate will use the default segment (`sequence_name='default'`) from the hibernate_sequences table.

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