1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73
|
<!--$Id: intro.html,v 1.1.1.1 2003/11/20 22:14:20 toshok Exp $-->
<!--Copyright 1997-2002 by Sleepycat Software, Inc.-->
<!--All rights reserved.-->
<!--See the file LICENSE for redistribution information.-->
<html>
<head>
<title>Berkeley DB Reference Guide: Introduction</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++">
</head>
<body bgcolor=white>
<a name="2"><!--meow--></a>
<table width="100%"><tr valign=top>
<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Berkeley DB Replication</dl></h3></td>
<td align=right><a href="../../ref/transapp/faq.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../reftoc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/rep/id.html"><img src="../../images/next.gif" alt="Next"></a>
</td></tr></table>
<p>
<h1 align=center>Introduction</h1>
<p>Berkeley DB includes support for building highly available applications based
on replication. Berkeley DB replication groups consist of some number of
independently configured database environments. There is a single
<i>master</i> database environment and one or more <i>client</i>
database environments. Master environments support both database reads
and writes; client environments support only database reads. If the
master environment fails, applications may upgrade a client to be the
new master. The database environments might be on separate computers,
on separate hardware partitions in a non-uniform memory access (NUMA)
system, or on separate disks in a single server. As always with Berkeley DB
environments, any number of concurrent processes or threads may access
a database environment. In the case of a master environment, any number
of threads of control may read and write the environment, and in the
case of a client environment, any number of threads of control may read
the environment.
<p>Applications may be written to provide various degrees of consistency
between the master and clients. The system can be run synchronously
such that replicas are guaranteed to be up-to-date with all committed
transactions, but doing so may incur a significant performance penalty.
Higher performance solutions sacrifice total consistency, allowing the
clients to be out of date for an application-controlled amount of time.
<p>While Berkeley DB includes the database infrastructure necessary to construct
highly available database environments, applications must still provide
some critical components:
<p><ol>
<p><li>The application is responsible for providing the communication
infrastructure. Applications may use whatever wire protocol is
appropriate for their application (for example, RPC, TCP/IP, UDP, VI or
message-passing over the backplane).
<p><li>The application is responsible for naming. Berkeley DB refers to the members
of a replication group using an application-provided ID, and
applications must map that ID to a particular database environment or
communication channel.
<p><li>The application is responsible for monitoring the status of the master
and clients, and identifying any unavailable database environments.
<p><li>The application must provide whatever security policies are needed.
For example, the application may choose to encrypt data, use a secure
socket layer, or do nothing at all. The level of security is left to
the sole discretion of the application.
</ol>
<!--$Id: intro.html,v 1.1.1.1 2003/11/20 22:14:20 toshok Exp $-->
<p><table border=1 align=center>
<tr><th>Replication and Related Methods</th><th>Description</th></tr>
<tr><td><a href="../../api_c/rep_transport.html">DB_ENV->set_rep_transport</a></td><td>Configure replication transport</td></tr>
<tr><td><a href="../../api_c/rep_elect.html">DB_ENV->rep_elect</a></td><td>Hold a replication election</td></tr>
<tr><td><a href="../../api_c/rep_limit.html">DB_ENV->set_rep_limit</a></td><td>Limit data sent in response to a single message</td></tr>
<tr><td><a href="../../api_c/rep_message.html">DB_ENV->rep_process_message</a></td><td>Process a replication message</td></tr>
<tr><td><a href="../../api_c/rep_start.html">DB_ENV->rep_start</a></td><td>Configure an environment for replication</td></tr>
<tr><td><a href="../../api_c/rep_stat.html">DB_ENV->rep_stat</a></td><td>Replication statistics</td></tr>
</table>
<table width="100%"><tr><td><br></td><td align=right><a href="../../ref/transapp/faq.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../reftoc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/rep/id.html"><img src="../../images/next.gif" alt="Next"></a>
</td></tr></table>
<p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font>
</body>
</html>
|