how does hibernate generator increment handle deletes

This is how i am using the g开发者_如何学Cenerator:

    <id name="id" column="column_name">
        <generator class="increment"/>
    </id>

private Integer id;

The behaviour that I am seeing is:

1. create the first object
2. hibernate assigns id = 1
3. delete that object
4. shut down the server and restart it (added this after the answer)
5. create a second object
6. hibernate assignes id = 1

note: I expected the new number to be 2, even though 1 doesnt exist anymore.

I have only tested this using HSQLDB.

Question: Is this expected behaviour?

AFAICT in the source, the next number should be 2 https://github.com/hibernate/hibernate-core/blob/master/hibernate-core/src/main/java/org/hibernate/id/IncrementGenerator.java#L68

Update: As per Ralph's answer, if I skip step 4 (dont shut down the server), it increments correctly. Its because the value gets set to max(id) on start up, and stored in memory after that.

The IncrementGenerator is initialized with "select max(" + column + ") from " + buf.toString(); where column is the ID column.

This means every time a new IncrementGenerator is created (more precise: the first time generate is invoked after configure is invoked) the id counter will be "reseted" to the max value from the DB.