<!--$Id--> <!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--> <!--All rights reserved.--> <html> <head> <title>Berkeley DB: DbEnv::set_flags</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><tr valign=top> <td> <h1>DbEnv::set_flags</h1> </td> <td width="1%"> <a href="../api_cxx/cxx_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> </td></tr></table> <hr size=1 noshade> <tt> <h3><pre> #include <db_cxx.h> <p> int DbEnv::set_flags(u_int32_t flags, int onoff); </pre></h3> <h1>Description</h1> <p>The <b>flags</b> value must be set to 0 or by bitwise inclusively <b>OR</b>'ing together one or more of the following values. If <b>onoff</b> is zero, the specified flags are cleared, otherwise they are set. <p><dl compact> <p><dt><a name="DB_CDB_ALLDB">DB_CDB_ALLDB</a><dd>For Berkeley DB Concurrent Data Store applications, perform locking on an environment-wide basis rather than per-database. This flag may only be used to configure Berkeley DB before the <a href="../api_cxx/env_open.html">DbEnv::open</a> interface is called. <p><dt><a name="DB_NOMMAP">DB_NOMMAP</a><dd>Copy read-only database files in this environment into the local cache instead of potentially mapping them into process memory (see the description of the <a href="../api_cxx/env_set_mp_mmapsize.html">DbEnv::set_mp_mmapsize</a> method for further information). <p><dt><a name="DB_TXN_NOSYNC">DB_TXN_NOSYNC</a><dd>Do not synchronously flush the log on transaction commit or prepare. This means that transactions exhibit the ACI (atomicity, consistency and isolation) properties, but not D (durability), i.e., database integrity will be maintained but it is possible that some number of the most recently committed transactions may be undone during recovery instead of being redone. <p>The number of transactions that are potentially at risk is governed by how often the log is checkpointed (see <a href="../utility/db_checkpoint.html">db_checkpoint</a> for more information) and how many log updates can fit on a single log page. </dl> <p>The DbEnv::set_flags method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success. <p>The database environment's flag values may also be set using the environment's <b>DB_CONFIG</b> file. The syntax of the entry in that file is a single line with the string "set_flags", one or more whitespace characters, and the interface flag argument as a string, for example, "set_flags DB_TXN_NOSYNC". Because the <b>DB_CONFIG</b> file is read when the database environment is opened, it will silently overrule configuration done before that time. <h1>Errors</h1> <p><dl compact> <p><dt>EINVAL<dd>An invalid flag value or parameter was specified. </dl> <h3>Class</h3> <a href="../api_cxx/dbenv_class.html">DbEnv</a> <h1>See Also</h1> <a href="../api_cxx/env_close.html">DbEnv::close</a>, <a href="../api_cxx/env_open.html">DbEnv::open</a>, <a href="../api_cxx/env_remove.html">DbEnv::remove</a>, <a href="../api_cxx/db_err.html">DbEnv::err</a>, <a href="../api_cxx/env_strerror.html">DbEnv::strerror</a>, <a href="../api_cxx/env_version.html">DbEnv::version</a>, <a href="../api_cxx/env_set_cachesize.html">DbEnv::set_cachesize</a>, <a href="../api_cxx/env_set_errcall.html">DbEnv::set_errcall</a>, <a href="../api_cxx/env_set_errfile.html">DbEnv::set_errfile</a>, <a href="../api_cxx/env_set_error_stream.html">DbEnv::set_error_stream</a>, <a href="../api_cxx/env_set_errpfx.html">DbEnv::set_errpfx</a>, <a href="../api_cxx/env_set_flags.html">DbEnv::set_flags</a>, <a href="../api_cxx/env_set_mutexlocks.html">DbEnv::set_mutexlocks</a>, <a href="../api_cxx/env_set_paniccall.html">DbEnv::set_paniccall</a>, and <a href="../api_cxx/env_set_verbose.html">DbEnv::set_verbose</a>. </tt> <table><tr><td><br></td><td width="1%"> <a href="../api_cxx/cxx_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font> </body> </html>