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<!--$Id: env_set_lg_max.so,v 10.45 2004/09/28 15:04:21 bostic Exp $-->
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<title>Berkeley DB: DB_ENV->set_lg_max</title>
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<h3>DB_ENV->set_lg_max</h3>
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<h3><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></h3>
<hr size=1 noshade>
<h3>Description: DB_ENV->set_lg_max</h3>
<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 <b>DB_CONFIG</b> 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 <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 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>
<h3>Parameters</h3>
<dl compact>
<dt><b>lg_max</b><dd>The <b>lg_max</b> parameter is the size of a single log file, in bytes.
</dl>
<h3>Errors</h3>
<p>The DB_ENV->set_lg_max method
may fail and return one of the following non-zero errors:</p>
<dl compact>
<dt>EINVAL<dd>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.
</dl>
<hr size=1 noshade>
<h3>Description: DB_ENV->get_lg_max</h3>
<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>
<h3>Parameters</h3>
<dl compact>
<dt><b>lg_maxp</b><dd>The DB_ENV->get_lg_max method returns the
maximum log file size in <b>lg_maxp</b>.
</dl>
<hr size=1 noshade>
<h3>Class</h3>
<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>
<h3>See Also</h3>
<a href="../api_c/log_list.html">Logging Subsystem and Related Methods</a>
</tt>
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