<!--$Id: env_set_lg_max.so,v 10.45 2004/09/28 15:04:21 bostic Exp $--> <!--Copyright (c) 1997,2008 Oracle. All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: DB_ENV->set_lg_max</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <table width="100%"><tr valign=top> <td> <b>DB_ENV->set_lg_max</b> </td> <td align=right> <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></td> </tr></table> <hr size=1 noshade> <tt> <b><pre> #include <db.h> <p> int DB_ENV->set_lg_max(DB_ENV *dbenv, u_int32_t lg_max); <p> int DB_ENV->get_lg_max(DB_ENV *dbenv, u_int32_t *lg_maxp); </pre></b> <hr size=1 noshade> <b>Description: DB_ENV->set_lg_max</b> <p>Set the maximum size of a single file in the log, in bytes. Because <a href="../api_c/lsn_class.html">DB_LSN</a> file offsets are unsigned four-byte values, the set value may not be larger than the maximum unsigned four-byte value.</p> <p>When the logging subsystem is configured for on-disk logging, the default size of a log file is 10MB.</p> <p>When the logging subsystem is configured for in-memory logging, the default size of a log file is 256KB. In addition, the configured log buffer size must be larger than the log file size. (The logging subsystem divides memory configured for in-memory log records into "files", as database environments configured for in-memory log records may exchange log records with other members of a replication group, and those members may be configured to store log records on-disk.) When choosing log buffer and file sizes for in-memory logs, applications should ensure the in-memory log buffer size is large enough that no transaction will ever span the entire buffer, and avoid a state where the in-memory buffer is full and no space can be freed because a transaction that started in the first log "file" is still active.</p> <p>See <a href="../ref/log/limits.html">Log File Limits</a> for more information.</p> <p>The database environment's log file size may also be configured using the environment's <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file. The syntax of the entry in that file is a single line with the string "set_lg_max", one or more whitespace characters, and the size in bytes. Because the <a href="../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a> file is read when the database environment is opened, it will silently overrule configuration done before that time.</p> <p>The DB_ENV->set_lg_max method configures a database environment, not only operations performed using the specified <a href="../api_c/env_class.html">DB_ENV</a> handle.</p> <p>The DB_ENV->set_lg_max method may be called at any time during the life of the application.</p> If no size is specified by the application, the size last specified for the database region will be used, or if no database region previously existed, the default will be used. <p>The DB_ENV->set_lg_max method returns a non-zero error value on failure and 0 on success. </p> <b>Parameters</b> <br> <b>lg_max</b><ul compact><li>The <b>lg_max</b> parameter is the size of a single log file, in bytes.</ul> <br> <br><b>Errors</b> <p>The DB_ENV->set_lg_max method may fail and return one of the following non-zero errors:</p> <br> <b>EINVAL</b><ul compact><li>If the method was called after <a href="../api_c/env_open.html">DB_ENV->open</a> was called; the size of the log file is less than four times the size of the in-memory log buffer; The specified log file size was too large; or if an invalid flag value or parameter was specified.</ul> <br> <hr size=1 noshade> <b>Description: DB_ENV->get_lg_max</b> <p>The DB_ENV->get_lg_max method returns the maximum log file size.</p> <p>The DB_ENV->get_lg_max method may be called at any time during the life of the application.</p> <p>The DB_ENV->get_lg_max method returns a non-zero error value on failure and 0 on success. </p> <b>Parameters</b> <br> <b>lg_maxp</b><ul compact><li>The DB_ENV->get_lg_max method returns the maximum log file size in <b>lg_maxp</b>.</ul> <br> <hr size=1 noshade> <br><b>Class</b> <a href="../api_c/env_class.html">DB_ENV</a>, <a href="../api_c/logc_class.html">DB_LOGC</a>, <a href="../api_c/lsn_class.html">DB_LSN</a> <br><b>See Also</b> <a href="../api_c/log_list.html">Logging Subsystem and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <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> </td></tr></table> <p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font> </body> </html>