2011-09-13 17:44:24 +00:00
|
|
|
|
<?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>Specifying a Berkeley DB schema using SQL DDL</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 Programmer's Reference Guide" />
|
|
|
|
|
|
<link rel="up" href="am_misc.html" title="Chapter 4. Access Method Wrapup" />
|
|
|
|
|
|
<link rel="prev" href="am_misc_diskspace.html" title="Disk space requirements" />
|
|
|
|
|
|
<link rel="next" href="am_misc_tune.html" title="Access method tuning" />
|
|
|
|
|
|
</head>
|
|
|
|
|
|
<body>
|
|
|
|
|
|
<div xmlns="" class="navheader">
|
|
|
|
|
|
<div class="libver">
|
2012-11-14 21:35:20 +00:00
|
|
|
|
<p>Library Version 11.2.5.3</p>
|
2011-09-13 17:44:24 +00:00
|
|
|
|
</div>
|
|
|
|
|
|
<table width="100%" summary="Navigation header">
|
|
|
|
|
|
<tr>
|
|
|
|
|
|
<th colspan="3" align="center">Specifying a Berkeley DB schema using SQL DDL</th>
|
|
|
|
|
|
</tr>
|
|
|
|
|
|
<tr>
|
|
|
|
|
|
<td width="20%" align="left"><a accesskey="p" href="am_misc_diskspace.html">Prev</a> </td>
|
|
|
|
|
|
<th width="60%" align="center">Chapter 4.
|
|
|
|
|
|
Access Method Wrapup
|
|
|
|
|
|
</th>
|
|
|
|
|
|
<td width="20%" align="right"> <a accesskey="n" href="am_misc_tune.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="am_misc_db_sql"></a>Specifying a Berkeley DB schema using SQL DDL</h2>
|
|
|
|
|
|
</div>
|
|
|
|
|
|
</div>
|
|
|
|
|
|
</div>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
When starting a new Berkeley DB project, much of the code that you
|
|
|
|
|
|
must write is dedicated to defining the BDB environment: what
|
|
|
|
|
|
databases it contains, the types of the databases, and so forth.
|
|
|
|
|
|
Also, since records in BDB are just byte arrays, you must write
|
|
|
|
|
|
code that assembles and interprets these byte arrays.
|
|
|
|
|
|
</p>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
Much of this code can be written automatically (in C) by the
|
|
|
|
|
|
db_sql_codegen utility. To use it, you first specify the schema of your Berkeley
|
|
|
|
|
|
DB environment in SQL Data Definition Language (DDL). Then you
|
|
|
|
|
|
invoke the db_sql_codegen command, giving the DDL as input.
|
|
|
|
|
|
<span class="command"><strong>db_sql_codegen</strong></span> reads the DDL, and writes C code that
|
|
|
|
|
|
implements a storage-layer API suggested by the DDL.
|
|
|
|
|
|
</p>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
The generated API includes a general-purpose initialization
|
|
|
|
|
|
function, which sets up the environment and the databases (creating
|
|
|
|
|
|
them if they don't already exist). It also includes C structure
|
|
|
|
|
|
declarations for each record type, and numerous specialized
|
|
|
|
|
|
functions for storing and retrieving those records.
|
|
|
|
|
|
</p>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
<span class="command"><strong>db_sql_codegen</strong></span> can also produce a simple test program
|
|
|
|
|
|
that exercises the generated API. This program is useful as an
|
|
|
|
|
|
example of how to use the API. It contains calls to all of the
|
|
|
|
|
|
interface functions, along with commentary explaining what the code
|
|
|
|
|
|
is doing.
|
|
|
|
|
|
</p>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
Once the storage layer API is produced, your application may use it
|
|
|
|
|
|
as is, or you may customize it as much as you like by editing the
|
|
|
|
|
|
generated source code. Be warned, however:
|
|
|
|
|
|
<span class="command"><strong>db_sql_codegen</strong></span> is a one-way process; there is no way to
|
|
|
|
|
|
automatically incorporate customizations into newly generated code,
|
|
|
|
|
|
if you decide to run <span class="command"><strong>db_sql_codegen</strong></span> again.
|
|
|
|
|
|
</p>
|
|
|
|
|
|
<p>
|
|
|
|
|
|
To learn more about <span class="command"><strong>db_sql_codegen</strong></span>, please consult the
|
|
|
|
|
|
db_sql_codegen utility manual page in the Berkeley DB C API Reference Guide.
|
|
|
|
|
|
</p>
|
|
|
|
|
|
</div>
|
|
|
|
|
|
<div class="navfooter">
|
|
|
|
|
|
<hr />
|
|
|
|
|
|
<table width="100%" summary="Navigation footer">
|
|
|
|
|
|
<tr>
|
|
|
|
|
|
<td width="40%" align="left"><a accesskey="p" href="am_misc_diskspace.html">Prev</a> </td>
|
|
|
|
|
|
<td width="20%" align="center">
|
|
|
|
|
|
<a accesskey="u" href="am_misc.html">Up</a>
|
|
|
|
|
|
</td>
|
|
|
|
|
|
<td width="40%" align="right"> <a accesskey="n" href="am_misc_tune.html">Next</a></td>
|
|
|
|
|
|
</tr>
|
|
|
|
|
|
<tr>
|
|
|
|
|
|
<td width="40%" align="left" valign="top">Disk space requirements </td>
|
|
|
|
|
|
<td width="20%" align="center">
|
|
|
|
|
|
<a accesskey="h" href="index.html">Home</a>
|
|
|
|
|
|
</td>
|
|
|
|
|
|
<td width="40%" align="right" valign="top"> Access method tuning</td>
|
|
|
|
|
|
</tr>
|
|
|
|
|
|
</table>
|
|
|
|
|
|
</div>
|
|
|
|
|
|
</body>
|
|
|
|
|
|
</html>
|
