mirror of
https://github.com/berkeleydb/libdb.git
synced 2024-11-17 01:26:25 +00:00
237 lines
8.8 KiB
HTML
237 lines
8.8 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||
<title>More Secondary Key Indices</title>
|
||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||
<link rel="start" href="index.html" title="Berkeley DB Collections Tutorial" />
|
||
<link rel="up" href="UsingSecondaries.html" title="Chapter 3. Using Secondary Indices" />
|
||
<link rel="prev" href="UsingSecondaries.html" title="Chapter 3. Using Secondary Indices" />
|
||
<link rel="next" href="indexedcollections.html" title="Creating Indexed Collections" />
|
||
</head>
|
||
<body>
|
||
<div xmlns="" class="navheader">
|
||
<div class="libver">
|
||
<p>Library Version 11.2.5.2</p>
|
||
</div>
|
||
<table width="100%" summary="Navigation header">
|
||
<tr>
|
||
<th colspan="3" align="center">
|
||
|
||
<span xmlns="http://www.w3.org/1999/xhtml">More Secondary Key Indices</span>
|
||
</th>
|
||
</tr>
|
||
<tr>
|
||
<td width="20%" align="left"><a accesskey="p" href="UsingSecondaries.html">Prev</a> </td>
|
||
<th width="60%" align="center">Chapter 3.
|
||
Using Secondary Indices
|
||
</th>
|
||
<td width="20%" align="right"> <a accesskey="n" href="indexedcollections.html">Next</a></td>
|
||
</tr>
|
||
</table>
|
||
<hr />
|
||
</div>
|
||
<div class="sect1" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h2 class="title" style="clear: both"><a id="openingforeignkeys"></a>
|
||
|
||
<span>More Secondary Key Indices</span>
|
||
</h2>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
This section builds on the prior section describing secondary key indices.
|
||
Two more secondary key indices are defined for indexing the Shipment record
|
||
by PartNumber and by SupplierNumber.
|
||
</p>
|
||
<p>
|
||
The <code class="classname">SampleDatabase</code> class is extended to open the
|
||
Shipment-by-Part and Shipment-by-Supplier secondary key
|
||
indices.
|
||
</p>
|
||
<a id="index_java_sampledatabase1"></a>
|
||
<pre class="programlisting"><strong class="userinput"><code>import com.sleepycat.bind.serial.SerialSerialKeyCreator;
|
||
import com.sleepycat.db.SecondaryConfig;
|
||
import com.sleepycat.db.SecondaryDatabase;</code></strong>
|
||
...
|
||
public class SampleDatabase
|
||
{
|
||
...
|
||
<strong class="userinput"><code> private static final String SHIPMENT_PART_INDEX =
|
||
"shipment_part_index";
|
||
private static final String SHIPMENT_SUPPLIER_INDEX =
|
||
"shipment_supplier_index";
|
||
...
|
||
private SecondaryDatabase shipmentByPartDb;
|
||
private SecondaryDatabase shipmentBySupplierDb;
|
||
...</code></strong>
|
||
public SampleDatabase(String homeDirectory)
|
||
throws DatabaseException, FileNotFoundException
|
||
{
|
||
...
|
||
SecondaryConfig secConfig = new SecondaryConfig();
|
||
secConfig.setTransactional(true);
|
||
secConfig.setAllowCreate(true);
|
||
secConfig.setType(DatabaseType.BTREE);
|
||
secConfig.setSortedDuplicates(true);
|
||
...
|
||
<strong class="userinput"><code> secConfig.setKeyCreator(
|
||
new ShipmentByPartKeyCreator(javaCatalog,
|
||
ShipmentKey.class,
|
||
ShipmentData.class,
|
||
PartKey.class));
|
||
shipmentByPartDb = env.openSecondaryDatabase(null,
|
||
SHIPMENT_PART_INDEX,
|
||
null,
|
||
shipmentDb,
|
||
secConfig);
|
||
|
||
secConfig.setKeyCreator(
|
||
new ShipmentBySupplierKeyCreator(javaCatalog,
|
||
ShipmentKey.class,
|
||
ShipmentData.class,
|
||
SupplierKey.class));
|
||
shipmentBySupplierDb = env.openSecondaryDatabase(null,
|
||
SHIPMENT_SUPPLIER_INDEX,
|
||
null,
|
||
shipmentDb,
|
||
secConfig);</code></strong>
|
||
...
|
||
}
|
||
} </pre>
|
||
<p>
|
||
The statements in this example are very similar to the statements used in
|
||
the previous section for opening a secondary index.
|
||
</p>
|
||
<p>
|
||
The application-defined <code class="classname">ShipmentByPartKeyCreator</code>
|
||
and <code class="classname">ShipmentBySupplierKeyCreator</code> classes are shown below. They
|
||
were used above to configure the secondary database objects.
|
||
</p>
|
||
<a id="index_shipmentbypartkeycreator"></a>
|
||
<pre class="programlisting">public class SampleDatabase
|
||
{
|
||
...
|
||
<strong class="userinput"><code> private static class ShipmentByPartKeyCreator
|
||
extends SerialSerialKeyCreator
|
||
{
|
||
private ShipmentByPartKeyCreator(ClassCatalog catalog,
|
||
Class primaryKeyClass,
|
||
Class valueClass,
|
||
Class indexKeyClass)
|
||
{
|
||
super(catalog, primaryKeyClass, valueClass, indexKeyClass);
|
||
}
|
||
|
||
public Object createSecondaryKey(Object primaryKeyInput,
|
||
Object valueInput)
|
||
{
|
||
ShipmentKey shipmentKey = (ShipmentKey) primaryKeyInput;
|
||
return new PartKey(shipmentKey.getPartNumber());
|
||
}
|
||
}
|
||
|
||
private static class ShipmentBySupplierKeyCreator
|
||
extends SerialSerialKeyCreator
|
||
{
|
||
private ShipmentBySupplierKeyCreator(ClassCatalog catalog,
|
||
Class primaryKeyClass,
|
||
Class valueClass,
|
||
Class indexKeyClass)
|
||
{
|
||
super(catalog, primaryKeyClass, valueClass, indexKeyClass);
|
||
}
|
||
|
||
public Object createSecondaryKey(Object primaryKeyInput,
|
||
Object valueInput)
|
||
{
|
||
ShipmentKey shipmentKey = (ShipmentKey) primaryKeyInput;
|
||
return new SupplierKey(shipmentKey.getSupplierNumber());
|
||
}
|
||
}</code></strong>
|
||
...
|
||
} </pre>
|
||
<p>
|
||
The key creator classes above are almost identical to the one
|
||
defined in the previous section for use with a secondary index. The
|
||
index key fields are different, of course, but the interesting
|
||
difference is that the index keys are extracted from the key, not
|
||
the value, of the Shipment record. This illustrates that an index
|
||
key may be derived from the primary database record key, value, or
|
||
both.
|
||
</p>
|
||
<p>
|
||
The following getter methods return the secondary database
|
||
objects for use by other classes in the example program.
|
||
</p>
|
||
<a id="index_sampledatabasegetters"></a>
|
||
<pre class="programlisting">public class SampleDatabase
|
||
{
|
||
...
|
||
<strong class="userinput"><code> public final SecondaryDatabase getShipmentByPartDatabase()
|
||
{
|
||
return shipmentByPartDb;
|
||
}
|
||
|
||
public final SecondaryDatabase getShipmentBySupplierDatabase()
|
||
{
|
||
return shipmentBySupplierDb;
|
||
}</code></strong>
|
||
...
|
||
} </pre>
|
||
<p>
|
||
The following statements close the secondary databases.
|
||
</p>
|
||
<a id="index_close2"></a>
|
||
<pre class="programlisting">public class SampleDatabase
|
||
{
|
||
...
|
||
public void close()
|
||
throws DatabaseException {
|
||
|
||
supplierByCityDb.close();
|
||
<strong class="userinput"><code> shipmentByPartDb.close();
|
||
shipmentBySupplierDb.close();</code></strong>
|
||
partDb.close();
|
||
supplierDb.close();
|
||
shipmentDb.close();
|
||
javaCatalog.close();
|
||
env.close();
|
||
}
|
||
...
|
||
} </pre>
|
||
<p>
|
||
Secondary databases must be closed before closing their
|
||
associated primary database.
|
||
</p>
|
||
</div>
|
||
<div class="navfooter">
|
||
<hr />
|
||
<table width="100%" summary="Navigation footer">
|
||
<tr>
|
||
<td width="40%" align="left"><a accesskey="p" href="UsingSecondaries.html">Prev</a> </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="u" href="UsingSecondaries.html">Up</a>
|
||
</td>
|
||
<td width="40%" align="right"> <a accesskey="n" href="indexedcollections.html">Next</a></td>
|
||
</tr>
|
||
<tr>
|
||
<td width="40%" align="left" valign="top">Chapter 3.
|
||
Using Secondary Indices
|
||
</td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="h" href="index.html">Home</a>
|
||
</td>
|
||
<td width="40%" align="right" valign="top">
|
||
Creating Indexed Collections
|
||
</td>
|
||
</tr>
|
||
</table>
|
||
</div>
|
||
</body>
|
||
</html>
|