mirror of
https://github.com/berkeleydb/libdb.git
synced 2024-11-17 01:26:25 +00:00
219 lines
9.6 KiB
HTML
219 lines
9.6 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>Developing a DB Collections Application</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="intro.html" title="Chapter 1. Introduction" />
|
|||
|
|
<link rel="prev" href="intro.html" title="Chapter 1. Introduction" />
|
|||
|
|
<link rel="next" href="tutorialintroduction.html" title="Tutorial Introduction" />
|
|||
|
|
</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">Developing a DB Collections Application</th>
|
|||
|
|
</tr>
|
|||
|
|
<tr>
|
|||
|
|
<td width="20%" align="left"><a accesskey="p" href="intro.html">Prev</a> </td>
|
|||
|
|
<th width="60%" align="center">Chapter 1.
|
|||
|
|
Introduction
|
|||
|
|
</th>
|
|||
|
|
<td width="20%" align="right"> <a accesskey="n" href="tutorialintroduction.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="developing"></a>Developing a DB Collections Application</h2>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<p>
|
|||
|
|
There are several important choices to make when developing an
|
|||
|
|
application using the DB Java Collections API.
|
|||
|
|
</p>
|
|||
|
|
<div class="orderedlist">
|
|||
|
|
<ol type="1">
|
|||
|
|
<li>
|
|||
|
|
<p>
|
|||
|
|
Choose the Berkeley DB Environment
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
Depending on your application's concurrency and transactional
|
|||
|
|
requirements, you may choose one of the three Berkeley DB
|
|||
|
|
Environments: Data Store, Concurrent Data Store, or
|
|||
|
|
Transactional Data Store. For details on creating and
|
|||
|
|
configuring the environment, see the
|
|||
|
|
<em class="citetitle">Berkeley DB Programmer's Reference Guide</em>
|
|||
|
|
</p>
|
|||
|
|
</li>
|
|||
|
|
<li>
|
|||
|
|
<p>
|
|||
|
|
Choose the Berkeley DB Access Method
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
For each Berkeley DB datastore, you may choose from any of the
|
|||
|
|
four Berkeley DB access methods — BTREE, HASH, RECNO, or
|
|||
|
|
QUEUE
|
|||
|
|
<span class="html">
|
|||
|
|
(<a class="ulink" href="../../java/com/sleepycat/db/DatabaseType.html#BTREE" target="_top">DatabaseType.BTREE</a>,
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/db/DatabaseType.html#HASH" target="_top">DatabaseType.HASH</a>,
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/db/DatabaseType.html#RECNO" target="_top">DatabaseType.RECNO</a>,
|
|||
|
|
or
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/db/DatabaseType.html#QUEUE" target="_top">DatabaseType.QUEUE</a>.)
|
|||
|
|
</span>
|
|||
|
|
— and a number of other database options. Your choice
|
|||
|
|
depends on several factors such as whether you need ordered
|
|||
|
|
keys, unique keys, record number access, and so forth. For more
|
|||
|
|
information on access methods, see the
|
|||
|
|
<em class="citetitle">Berkeley DB Programmer's Reference Guide</em>.
|
|||
|
|
</p>
|
|||
|
|
</li>
|
|||
|
|
<li>
|
|||
|
|
<p>
|
|||
|
|
Choose the Format for Keys and Values
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
For each database you may choose a binding format for the keys
|
|||
|
|
and values. For example, the tuple format is useful for keys
|
|||
|
|
because it has a deterministic sort order. The serial format is
|
|||
|
|
useful for values if you want to store arbitrary Java objects. In
|
|||
|
|
some cases a custom format may be appropriate. For details on
|
|||
|
|
choosing a binding format see
|
|||
|
|
<a class="xref" href="collectionOverview.html#UsingDataBindings" title="Using Data Bindings">
|
|||
|
|
Using Data Bindings
|
|||
|
|
</a>.
|
|||
|
|
</p>
|
|||
|
|
</li>
|
|||
|
|
<li>
|
|||
|
|
<p>
|
|||
|
|
Choose the Binding for Keys and Values
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
With the serial data format you do not have to create a binding
|
|||
|
|
for each Java class that is stored since Java serialization is
|
|||
|
|
used. But for other formats a binding must be defined that
|
|||
|
|
translates between stored byte arrays and Java objects. For details
|
|||
|
|
see
|
|||
|
|
<a class="xref" href="collectionOverview.html#UsingDataBindings" title="Using Data Bindings">
|
|||
|
|
Using Data Bindings
|
|||
|
|
</a>.
|
|||
|
|
</p>
|
|||
|
|
</li>
|
|||
|
|
<li>
|
|||
|
|
<p>
|
|||
|
|
Choose Secondary Indices
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
Any database that has unique keys may have any number of
|
|||
|
|
secondary indices. A secondary index has keys that are derived from
|
|||
|
|
data values in the primary database. This allows lookup and
|
|||
|
|
iteration of objects in the database by its index keys.
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
For each index you must define how the index keys are derived from the data
|
|||
|
|
values using a
|
|||
|
|
|
|||
|
|
<span>
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/db/SecondaryKeyCreator.html" target="_top">SecondaryKeyCreator</a>.
|
|||
|
|
</span>
|
|||
|
|
For details see the
|
|||
|
|
|
|||
|
|
|
|||
|
|
<span>
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/db/SecondaryDatabase.html" target="_top">SecondaryDatabase</a>,
|
|||
|
|
</span>
|
|||
|
|
|
|||
|
|
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/db/SecondaryConfig.html" target="_top">SecondaryConfig</a>
|
|||
|
|
|
|||
|
|
and
|
|||
|
|
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/db/SecondaryKeyCreator.html" target="_top">SecondaryKeyCreator</a>
|
|||
|
|
|
|||
|
|
classes.
|
|||
|
|
</p>
|
|||
|
|
</li>
|
|||
|
|
<li>
|
|||
|
|
<p>
|
|||
|
|
Choose the Collection Interface for each Database
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
The standard Java Collection interfaces are used for accessing
|
|||
|
|
databases and secondary indices. The Map and Set interfaces may be
|
|||
|
|
used for any type of database. The Iterator interface is used
|
|||
|
|
through the Set interfaces. For more information on the collection
|
|||
|
|
interfaces see
|
|||
|
|
<a class="xref" href="UsingStoredCollections.html" title="Using Stored Collections">
|
|||
|
|
Using Stored Collections
|
|||
|
|
</a>.
|
|||
|
|
</p>
|
|||
|
|
</li>
|
|||
|
|
</ol>
|
|||
|
|
</div>
|
|||
|
|
<p>
|
|||
|
|
Any number of bindings and collections may be created for the
|
|||
|
|
same database. This allows multiple views of the same stored data.
|
|||
|
|
For example, a data store may be viewed as a Map of keys to values,
|
|||
|
|
a Set of keys, or a Collection of values. String values, for
|
|||
|
|
example, may be used with the built-in binding to the String class,
|
|||
|
|
or with a custom binding to another class that represents the
|
|||
|
|
string values differently.
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
It is sometimes desirable to use a Java class that encapsulates
|
|||
|
|
both a data key and a data value. For example, a Part object might
|
|||
|
|
contain both the part number (key) and the part name (value). Using
|
|||
|
|
the DB Java Collections API this type of object is called an
|
|||
|
|
"entity". An entity binding is used to translate between the Java
|
|||
|
|
object and the stored data key and value. Entity bindings may be
|
|||
|
|
used with all Collection types.
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
Please be aware that the provided DB Java Collections API collection classes
|
|||
|
|
do not conform completely to the interface contracts
|
|||
|
|
defined in the <code class="literal">java.util</code> package. For example, all
|
|||
|
|
iterators must be explicitly closed and the <code class="methodname">size()</code>
|
|||
|
|
method is not available. The differences between the DB Java Collections API
|
|||
|
|
collections and the standard Java collections are
|
|||
|
|
documented in
|
|||
|
|
<a class="xref" href="UsingStoredCollections.html#StoredVersusStandardCollections" title="Stored Collections Versus Standard Java Collections">
|
|||
|
|
Stored Collections Versus Standard Java Collections
|
|||
|
|
</a>.
|
|||
|
|
</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="navfooter">
|
|||
|
|
<hr />
|
|||
|
|
<table width="100%" summary="Navigation footer">
|
|||
|
|
<tr>
|
|||
|
|
<td width="40%" align="left"><a accesskey="p" href="intro.html">Prev</a> </td>
|
|||
|
|
<td width="20%" align="center">
|
|||
|
|
<a accesskey="u" href="intro.html">Up</a>
|
|||
|
|
</td>
|
|||
|
|
<td width="40%" align="right"> <a accesskey="n" href="tutorialintroduction.html">Next</a></td>
|
|||
|
|
</tr>
|
|||
|
|
<tr>
|
|||
|
|
<td width="40%" align="left" valign="top">Chapter 1.
|
|||
|
|
Introduction
|
|||
|
|
</td>
|
|||
|
|
<td width="20%" align="center">
|
|||
|
|
<a accesskey="h" href="index.html">Home</a>
|
|||
|
|
</td>
|
|||
|
|
<td width="40%" align="right" valign="top"> Tutorial Introduction</td>
|
|||
|
|
</tr>
|
|||
|
|
</table>
|
|||
|
|
</div>
|
|||
|
|
</body>
|
|||
|
|
</html>
|