<!--$Id: env_set_lg_bsize.so,v 10.31 2003/11/08 19:17:30 bostic Exp $--> <!--Copyright 1997-2003 by Sleepycat Software, Inc.--> <!--All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: DbEnv::set_lg_bsize</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>DbEnv::set_lg_bsize</h3> </td> <td align=right> <a href="../../db42-devel-4.2.52/api_cxx/api_index.html"><img src="../../db42-4.2.52/images/api.gif" alt="API"></a> <a href="../../db42-devel-4.2.52/ref/toc.html"><img src="../../db42-4.2.52/images/ref.gif" alt="Ref"></a> </td></tr></table> <hr size=1 noshade> <tt> <h3><pre> #include <db_cxx.h> <p> int DbEnv::set_lg_bsize(u_int32_t lg_bsize); <p> int DbEnv::get_lg_bsize(u_int32_t *lg_bsizep); </pre></h3> <hr size=1 noshade> <h3>Description: DbEnv::set_lg_bsize</h3> <a name="3"><!--meow--></a> <p>Set the size of the in-memory log buffer, in bytes. By default, or if the value is set to 0, a size of 32K is used. The size of the log file (see <a href="../../db42-devel-4.2.52/api_cxx/env_set_lg_max.html">DbEnv::set_lg_max</a>) must be at least four times the size of the in-memory log buffer.</p> <p>Log information is stored in-memory until the storage space fills up or transaction commit forces the information to be flushed to stable storage. In the presence of long-running transactions or transactions producing large amounts of data, larger buffer sizes can increase throughput.</p> <p>The database environment's log buffer size 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_lg_bsize", one or more whitespace characters, and the size in bytes. Because the <b>DB_CONFIG</b> file is read when the database environment is opened, it will silently overrule configuration done before that time.</p> <p>The DbEnv::set_lg_bsize method configures a database environment, not only operations performed using the specified <a href="../../db42-devel-4.2.52/api_cxx/env_class.html">DbEnv</a> handle.</p> <p>The DbEnv::set_lg_bsize method may not be called after the <a href="../../db42-devel-4.2.52/api_cxx/env_open.html">DbEnv::open</a> method is called. If the database environment already exists when <a href="../../db42-devel-4.2.52/api_cxx/env_open.html">DbEnv::open</a> is called, the information specified to DbEnv::set_lg_bsize will be ignored. </p> <p>The DbEnv::set_lg_bsize 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> <h3>Parameters</h3> <p><dl compact> <p><dt><b>lg_bsize</b><dd> The <b>lg_bsize</b> parameter is the size of the in-memory log buffer, in bytes. </dl> <h3>Errors</h3> <p>The DbEnv::set_lg_bsize method may fail and throw <a href="../../db42-devel-4.2.52/api_cxx/except_class.html">DbException</a>, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:</p> <p><dl compact> <p><dt>EINVAL<dd>If the method was called after <a href="../../db42-devel-4.2.52/api_cxx/env_open.html">DbEnv::open</a> was called; The size of the log file is less than four times the size of the in-memory log buffer; or if an invalid flag value or parameter was specified. </dl> <hr size=1 noshade> <h3>Description: DbEnv::get_lg_bsize</h3> <p>The DbEnv::get_lg_bsize method returns the size of the log buffer, in bytes.</p> <p>The DbEnv::get_lg_bsize method may be called at any time during the life of the application.</p> <p>The DbEnv::get_lg_bsize 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> <h3>Parameters</h3> <p><dl compact> <p><dt><b>lg_bsizep</b><dd> The DbEnv::get_lg_bsize method returns the size of the log buffer, in bytes in <b>lg_bsizep</b>. </dl> <hr size=1 noshade> <h3>Class</h3> <a href="../../db42-devel-4.2.52/api_cxx/env_class.html">DbEnv</a>, <a href="../../db42-devel-4.2.52/api_cxx/logc_class.html">DbLogc</a>, <a href="../../db42-devel-4.2.52/api_cxx/lsn_class.html">DbLsn</a> <h3>See Also</h3> <a href="../../db42-devel-4.2.52/api_cxx/log_list.html">Logging Subsystem and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../../db42-devel-4.2.52/api_cxx/api_index.html"><img src="../../db42-4.2.52/images/api.gif" alt="API"></a><a href="../../db42-devel-4.2.52/ref/toc.html"><img src="../../db42-4.2.52/images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1><a href="../../db42-devel-4.2.52/sleepycat/legal.html">Copyright (c) 1996-2003</a> <a href="http://www.sleepycat.com">Sleepycat Software, Inc.</a> - All rights reserved.</font> </body> </html>