1<!--$Id: env_class.so,v 10.45 2005/11/30 19:09:47 bostic Exp $--> 2<!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> 3<!--See the file LICENSE for redistribution information.--> 4<html> 5<head> 6<title>Berkeley DB: db_env_create</title> 7<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> 8<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> 9</head> 10<body bgcolor=white> 11<table width="100%"><tr valign=top> 12<td> 13<b>db_env_create</b> 14</td> 15<td align=right> 16<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a> 17<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td> 18</tr></table> 19<hr size=1 noshade> 20<tt> 21<b><pre> 22#include <db.h> 23<p> 24int 25db_env_create(DB_ENV **dbenvp, u_int32_t flags); 26</pre></b> 27<hr size=1 noshade> 28<b>Description: db_env_create</b> 29<p>The DB_ENV object is the handle for a Berkeley DB environment -- a 30collection including support for some or all of caching, locking, 31logging and transaction subsystems, as well as databases and log files. 32Methods of the DB_ENV handle are used to configure the 33environment as well as to operate on subsystems and databases in the 34environment.</p> 35<p>DB_ENV handles are free-threaded if the <a href="../api_c/env_open.html#DB_THREAD">DB_THREAD</a> flag 36is specified to the <a href="../api_c/env_open.html">DB_ENV->open</a> method when the environment is opened. 37The DB_ENV handle should not be closed while any other handle 38remains open that is using it as a reference (for example, <a href="../api_c/db_class.html">DB</a> 39or <a href="../api_c/txn_class.html">DB_TXN</a>). Once either the <a href="../api_c/env_close.html">DB_ENV->close</a> or 40<a href="../api_c/env_remove.html">DB_ENV->remove</a> methods are called, the handle may not be accessed again, 41regardless of the method's return.</p> 42<p>The db_env_create function creates a DB_ENV structure that 43is the handle for a Berkeley DB environment. This function allocates memory 44for the structure, returning a pointer to the structure in the memory 45to which <b>dbenvp</b> refers. To release the allocated memory and 46discard the handle, call the <a href="../api_c/env_close.html">DB_ENV->close</a> or <a href="../api_c/env_remove.html">DB_ENV->remove</a> methods.</p> 47<p>The DB_ENV handle contains a special field, "app_private", which 48is declared as type "void *". This field is provided for the use of 49the application program. It is initialized to NULL and is not further 50used by Berkeley DB in any way.</p> 51<p>The db_env_create method 52returns a non-zero error value on failure 53and 0 on success. 54</p> 55The <b>flags</b> parameter must be set to 0 or 56the following value: 57<br> 58<b><a name="DB_RPCCLIENT">DB_RPCCLIENT</a></b><ul compact><li>Create a client environment to connect to a server.</ul> 59<p>The DB_RPCCLIENT flag indicates to the system that this environment 60is remote on a server. The use of this flag causes the environment 61methods to use functions that call a server instead of local functions. 62Prior to making any environment or database method calls, the application 63must call the <a href="../api_c/env_set_rpc_server.html">DB_ENV->set_rpc_server</a> function to establish the 64connection to the server.</p> 65<br> 66<br><b>Errors</b> 67<hr size=1 noshade> 68<br><b>Class</b> 69DB_ENV 70<br><b>See Also</b> 71<a href="../api_c/env_list.html">Database Environments and Related Methods</a> 72</tt> 73<table width="100%"><tr><td><br></td><td align=right> 74<a href="../api_c/api_core.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> 75</td></tr></table> 76<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> 77</body> 78</html> 79
