6.4. MANUAL flush

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Both the `EntityManager` and the Hibernate `Session` define a `flush()` method that, when called, triggers a manual flush.
Hibernate also defines a `MANUAL` flush mode so the persistence context can only be flushed manually.

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<div id="flushing-manual-flush-example" class="exampleblock">
<div class="title">Example 271. `MANUAL` flushing</div>
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<div class="listingblock">
<div class="content">
<pre class="prettyprint highlight">`Person person = new Person("John Doe");
entityManager.persist(person);

Session session = entityManager.unwrap( Session.class);
session.setHibernateFlushMode( FlushMode.MANUAL );

assertTrue(((Number) entityManager
    .createQuery("select count(id) from Person")
    .getSingleResult()).intValue() == 0);

assertTrue(((Number) session
    .createSQLQuery("select count(*) from Person")
    .uniqueResult()).intValue() == 0);`</pre>
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</div>
<div class="listingblock">
<div class="content">
<pre class="prettyprint highlight">`SELECT COUNT(p.id) AS col_0_0_
FROM   Person p

SELECT COUNT(*)
FROM   Person`</pre>
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</div>
</div>
</div>
<div class="paragraph">

The `INSERT` statement was not executed because the persistence context because there was no manual `flush()` call.

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<div class="admonitionblock note">
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<tr>
<td class="icon">

</td>
<td class="content">
<div class="paragraph">

This mode is useful when using multi-request logical transactions and only the last request should flush the persistence context.

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</td>
</tr>
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<div class="sect2">