1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 6 <title>Database Open Flags</title> 7 <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> 8 <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> 9 <link rel="start" href="index.html" title="Getting Started with Berkeley DB" /> 10 <link rel="up" href="DB.html" title="Chapter 2. Databases" /> 11 <link rel="prev" href="coredbclose.html" title="Closing Databases" /> 12 <link rel="next" href="CoreDBAdmin.html" title="Administrative Methods" /> 13 </head> 14 <body> 15 <div class="navheader"> 16 <table width="100%" summary="Navigation header"> 17 <tr> 18 <th colspan="3" align="center">Database Open Flags</th> 19 </tr> 20 <tr> 21 <td width="20%" align="left"><a accesskey="p" href="coredbclose.html">Prev</a> </td> 22 <th width="60%" align="center">Chapter 2. Databases</th> 23 <td width="20%" align="right"> <a accesskey="n" href="CoreDBAdmin.html">Next</a></td> 24 </tr> 25 </table> 26 <hr /> 27 </div> 28 <div class="sect1" lang="en" xml:lang="en"> 29 <div class="titlepage"> 30 <div> 31 <div> 32 <h2 class="title" style="clear: both"><a id="DBOpenFlags"></a>Database Open Flags</h2> 33 </div> 34 </div> 35 </div> 36 <p> 37 The following are the flags that you may want to use at database open time. 38 Note that this list is not exhaustive — it includes only those flags likely 39 to be of interest for introductory, single-threaded 40 database applications. For a complete list of the flags available to you, see the 41 <em class="citetitle">Berkeley DB C API guide.</em> 42 43 </p> 44 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> 45 <h3 class="title">Note</h3> 46 <p> 47 To specify more than one flag on the call to 48 <span><code class="methodname">DB->open()</code>,</span> 49 50 you must bitwise inclusively OR them together: 51 </p> 52 <a id="c_db3"></a> 53 <pre class="programlisting">u_int32_t open_flags = DB_CREATE | DB_EXCL;</pre> 54 </div> 55 <div class="itemizedlist"> 56 <ul type="disc"> 57 <li> 58 <p> 59 <code class="literal">DB_CREATE</code> 60 </p> 61 <p> 62 If the database does not currently exist, create it. By default, the database open 63 fails if the database does not already exist. 64 </p> 65 </li> 66 <li> 67 <p> 68 <code class="literal">DB_EXCL</code> 69 </p> 70 <p> 71 Exclusive database creation. Causes the database open to fail if the database 72 already exists. This flag is only meaningful when used with 73 <code class="literal">DB_CREATE</code>. 74 </p> 75 </li> 76 <li> 77 <p> 78 <code class="literal">DB_RDONLY</code> 79 </p> 80 <p> 81 Open the database for read operations only. Causes any subsequent database write 82 operations to fail. 83 </p> 84 </li> 85 <li> 86 <p> 87 <code class="literal">DB_TRUNCATE</code> 88 </p> 89 <p> 90 Physically truncate (empty) the on-disk file that contains the database. 91 Causes DB to delete all databases physically contained in that file. 92 </p> 93 </li> 94 </ul> 95 </div> 96 </div> 97 <div class="navfooter"> 98 <hr /> 99 <table width="100%" summary="Navigation footer"> 100 <tr> 101 <td width="40%" align="left"><a accesskey="p" href="coredbclose.html">Prev</a> </td> 102 <td width="20%" align="center"> 103 <a accesskey="u" href="DB.html">Up</a> 104 </td> 105 <td width="40%" align="right"> <a accesskey="n" href="CoreDBAdmin.html">Next</a></td> 106 </tr> 107 <tr> 108 <td width="40%" align="left" valign="top">Closing Databases </td> 109 <td width="20%" align="center"> 110 <a accesskey="h" href="index.html">Home</a> 111 </td> 112 <td width="40%" align="right" valign="top"> Administrative Methods</td> 113 </tr> 114 </table> 115 </div> 116 </body> 117</html> 118