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SecondaryKey
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com.sleepycat.persist.model</FONT>
<BR>
Annotation Type SecondaryKey</H2>
<HR>
<DL>
<DT><PRE><FONT SIZE="-1">@Documented
@Retention(value=RUNTIME)
@Target(value=FIELD)
</FONT>public @interface <B>SecondaryKey</B></DL>
</PRE>
<P>
Indicates a secondary key field of an entity class. The value of the
secondary key field is a unique or non-unique identifier for the entity and
is accessed via a <A HREF="../../../../com/sleepycat/persist/SecondaryIndex.html" title="class in com.sleepycat.persist"><CODE>SecondaryIndex</CODE></A>.
<p><code>SecondaryKey</code> may appear on any number of fields in an entity
class, subclasses and superclasses. For a secondary key field in the entity
class or one of its superclasses, all entity instances will be indexed by
that field (if it is non-null). For a secondary key field in an entity
subclass, only instances of that subclass will be indexed by that field (if
it is non-null).</p>
<p>If a secondary key field is null, the entity will not be indexed by that
key. In other words, the entity cannot be queried by that secondary key nor
can the entity be found by iterating through the secondary index.</p>
<p>For a given entity class and its superclasses and subclasses, no two
secondary keys may have the same name. By default, the field name
identifies the secondary key and the secondary index for a given entity
class. <A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#name()"><CODE>name()</CODE></A> may be specified to override this default.</p>
<p>Using <A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#relate()"><CODE>relate()</CODE></A>, instances of the entity class are related to
secondary keys in a many-to-one, one-to-many, many-to-many, or one-to-one
relationship. This required property specifies the <em>cardinality</em> of
each side of the relationship.</p>
<p>A secondary key may optionally be used to form a relationship with
instances of another entity class using <A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#relatedEntity()"><CODE>relatedEntity()</CODE></A> and <A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#onRelatedEntityDelete()"><CODE>onRelatedEntityDelete()</CODE></A>. This establishes <em>foreign key constraints</em>
for the secondary key.</p>
<p>The secondary key field type must be an array or collection type when a
<em>x-to-many</em> relationship is used or a singular type when an
<em>x-to-one</em> relationship is used; see <A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#relate()"><CODE>relate()</CODE></A>.</p>
<p>The field type (or element type, when an array or collection type is
used) of a secondary key field must follow the same rules as for a <a href="PrimaryKey.html#keyTypes">primary key type</a>. The <a
href="PrimaryKey.html#sortOrder">key sort order</a> is also the same.</p>
<p>For a secondary key field with a collection type, a type parameter must
be used to specify the element type. For example <code>Collection<String></code>
is allowed but <code>Collection</code> is not.</p>
<P>
<P>
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<B>Required Element Summary</B></FONT></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> <A HREF="../../../../com/sleepycat/persist/model/Relationship.html" title="enum in com.sleepycat.persist.model">Relationship</A></CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#relate()">relate</A></B></CODE>
<BR>
Defines the relationship between instances of the entity class and the
secondary keys.</TD>
</TR>
</TABLE>
<!-- =========== ANNOTATION TYPE OPTIONAL MEMBER SUMMARY =========== -->
<A NAME="annotation_type_optional_element_summary"><!-- --></A>
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<TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2">
<B>Optional Element Summary</B></FONT></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#name()">name</A></B></CODE>
<BR>
Specifies the name of the key in order to use a name that is different
than the field name.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> <A HREF="../../../../com/sleepycat/persist/model/DeleteAction.html" title="enum in com.sleepycat.persist.model">DeleteAction</A></CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#onRelatedEntityDelete()">onRelatedEntityDelete</A></B></CODE>
<BR>
Specifies the action to take when a related entity is deleted having a
primary key value that exists as a secondary key value for this entity.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE> java.lang.Class</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#relatedEntity()">relatedEntity</A></B></CODE>
<BR>
Specifies the entity to which this entity is related, for establishing
foreign key constraints.</TD>
</TR>
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<P>
<!-- ============ ANNOTATION TYPE MEMBER DETAIL =========== -->
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<B>Element Detail</B></FONT></TH>
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<A NAME="relate()"><!-- --></A><H3>
relate</H3>
<PRE>
public abstract <A HREF="../../../../com/sleepycat/persist/model/Relationship.html" title="enum in com.sleepycat.persist.model">Relationship</A> <B>relate</B></PRE>
<DL>
<DD>Defines the relationship between instances of the entity class and the
secondary keys.
<p>The table below summarizes how to create all four variations of
relationships.</p>
<div>
<table border="yes">
<tr><th>Relationship</th>
<th>Field type</th>
<th>Key type</th>
<th>Example</th>
</tr>
<tr><td><A HREF="../../../../com/sleepycat/persist/model/Relationship.html#ONE_TO_ONE"><CODE>Relationship.ONE_TO_ONE</CODE></A></td>
<td>Singular</td>
<td>Unique</td>
<td>A person record with a unique social security number
key.</td>
</tr>
<tr><td><A HREF="../../../../com/sleepycat/persist/model/Relationship.html#MANY_TO_ONE"><CODE>Relationship.MANY_TO_ONE</CODE></A></td>
<td>Singular</td>
<td>Duplicates</td>
<td>A person record with a non-unique employer key.</td>
</tr>
<tr><td><A HREF="../../../../com/sleepycat/persist/model/Relationship.html#ONE_TO_MANY"><CODE>Relationship.ONE_TO_MANY</CODE></A></td>
<td>Array/Collection</td>
<td>Unique</td>
<td>A person record with multiple unique email address keys.</td>
</tr>
<tr><td><A HREF="../../../../com/sleepycat/persist/model/Relationship.html#MANY_TO_MANY"><CODE>Relationship.MANY_TO_MANY</CODE></A></td>
<td>Array/Collection</td>
<td>Duplicates</td>
<td>A person record with multiple non-unique organization
keys.</td>
</tr>
</table>
</div>
<p>For a <em>many-to-x</em> relationship, the secondary index will
have non-unique keys; in other words, duplicates will be allowed.
Conversely, for <em>one-to-x</em> relationship, the secondary index
will have unique keys.</p>
<p>For a <em>x-to-one</em> relationship, the secondary key field is
singular; in other words, it may not be an array or collection type.
Conversely, for a <em>x-to-many</em> relationship, the secondary key
field must be an array or collection type. A collection type is any
implementation of <CODE>Collection</CODE>.</p>
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
</DL>
</DL>
<A NAME="relatedEntity()"><!-- --></A><H3>
relatedEntity</H3>
<PRE>
public abstract java.lang.Class <B>relatedEntity</B></PRE>
<DL>
<DD>Specifies the entity to which this entity is related, for establishing
foreign key constraints. Values of this secondary key will be
constrained to the set of primary key values for the given entity class.
<p>The given class must be an entity class. This class is called the
<em>related entity</em> or <em>foreign entity</em>.</p>
<p>When a related entity class is specified, a check (foreign key
constraint) is made every time a new secondary key value is stored for
this entity, and every time a related entity is deleted.</p>
<p>Whenever a new secondary key value is stored for this entity, it is
checked to ensure it exists as a primary key value of the related
entity. If it does not, a <A HREF="../../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db"><CODE>DatabaseException</CODE></A> will be thrown
by the <A HREF="../../../../com/sleepycat/persist/PrimaryIndex.html" title="class in com.sleepycat.persist"><CODE>PrimaryIndex</CODE></A> <code>put</code> method.</p>
<p>Whenever a related entity is deleted and its primary key value exists
as a secondary key value for this entity, the action is taken that is
specified using the <A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#onRelatedEntityDelete()"><CODE>onRelatedEntityDelete()</CODE></A> property.</p>
<p>Together, these two checks guarantee that a secondary key value for
this entity will always exist as a primary key value for the related
entity. Note, however, that a transactional store must be configured
to guarantee this to be true in the face of a crash; see <A HREF="../../../../com/sleepycat/persist/StoreConfig.html#setTransactional(boolean)"><CODE>StoreConfig.setTransactional(boolean)</CODE></A>.</p>
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
</DL>
<DL>
<DT><B>Default:</B><DD>void.class</DD>
</DL>
</DL>
<HR>
<A NAME="onRelatedEntityDelete()"><!-- --></A><H3>
onRelatedEntityDelete</H3>
<PRE>
public abstract <A HREF="../../../../com/sleepycat/persist/model/DeleteAction.html" title="enum in com.sleepycat.persist.model">DeleteAction</A> <B>onRelatedEntityDelete</B></PRE>
<DL>
<DD>Specifies the action to take when a related entity is deleted having a
primary key value that exists as a secondary key value for this entity.
<p><em>Note:</em> This property only applies when <A HREF="../../../../com/sleepycat/persist/model/SecondaryKey.html#relatedEntity()"><CODE>relatedEntity()</CODE></A>
is specified to define the related entity.</p>
<p>The default action, <A HREF="../../../../com/sleepycat/persist/model/DeleteAction.html#ABORT"><CODE>ABORT</CODE></A>, means that a
<A HREF="../../../../com/sleepycat/db/DatabaseException.html" title="class in com.sleepycat.db"><CODE>DatabaseException</CODE></A> is thrown in order to abort the current
transaction.</p>
<p>If <A HREF="../../../../com/sleepycat/persist/model/DeleteAction.html#CASCADE"><CODE>CASCADE</CODE></A> is specified, then this
entity will be deleted also. This in turn could trigger further
deletions, causing a cascading effect.</p>
<p>If <A HREF="../../../../com/sleepycat/persist/model/DeleteAction.html#NULLIFY"><CODE>NULLIFY</CODE></A> is specified, then the
secondary key in this entity is set to null and this entity is updated.
If the key field type is singular, the field value is set to null;
therefore, to specify <code>NULLIFY</code> for a singular key field type, a
primitive wrapper type must be used instead of a primitive type. If the
key field type is an array or collection type, the key is deleted from
the array (the array is resized) or from the collection (using <CODE>Collection.remove</CODE>).</p>
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
</DL>
<DL>
<DT><B>Default:</B><DD>com.sleepycat.persist.model.DeleteAction.ABORT</DD>
</DL>
</DL>
<HR>
<A NAME="name()"><!-- --></A><H3>
name</H3>
<PRE>
public abstract java.lang.String <B>name</B></PRE>
<DL>
<DD>Specifies the name of the key in order to use a name that is different
than the field name.
<p>This is convenient when prefixes or suffices are used on field names.
For example:</p>
<pre class="code">
class Person {
@SecondaryKey(relate=MANY_TO_ONE, relatedEntity=Person.class, name="parentSsn")
String m_parentSsn;
}</pre>
<p>It can also be used to uniquely name a key when multiple secondary
keys for a single entity class have the same field name. For example,
an entity class and its subclass may both have a field named 'date',
and both fields are used as secondary keys. The <code>name</code> property
can be specified for one or both fields to give each key a unique
name.</p>
<P>
<DD><DL>
</DL>
</DD>
<DD><DL>
</DL>
<DL>
<DT><B>Default:</B><DD>""</DD>
</DL>
</DL>
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