Sets the size of the in-memory log buffer, in bytes.
</p>
<p>
When the logging subsystem is configured for on-disk logging, the
default size of the in-memory log buffer is approximately 32KB. 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>
When the logging subsystem is configured for in-memory logging, the
default size of the in-memory log buffer is 1MB. Log information is
stored in-memory until the storage space fills up or transaction abort
or commit frees up the memory for new transactions. In the presence
of long-running transactions or transactions producing large amounts
of data, the buffer size must be sufficient to hold all log
information that can accumulate during the longest running
transaction. 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>
The database environment's log buffer size may also be configured
using the environment's <ahref="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG"class="olink">DB_CONFIG</a> 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
<ahref="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG"class="olink">DB_CONFIG</a> file is read when the database environment is opened,
it will silently overrule configuration done before that time.
</p>
<p>
The <codeclass="methodname">DB_ENV->set_lg_bsize()</code> method configures a database environment,
not only operations performed using the specified <aclass="link"href="env.html"title="Chapter5. The DB_ENV Handle">DB_ENV</a> handle.
</p>
<p>
The <codeclass="methodname">DB_ENV->set_lg_bsize()</code> method may not be called after the
<aclass="xref"href="envopen.html"title="DB_ENV->open()">DB_ENV->open()</a> method is called.
If the database environment already exists when
<aclass="xref"href="envopen.html"title="DB_ENV->open()">DB_ENV->open()</a> is called, the
information specified to <codeclass="methodname">DB_ENV->set_lg_bsize()</code> will be ignored.
</p>
<p>
The <codeclass="methodname">DB_ENV->set_lg_bsize()</code><span>
<span>
method returns a non-zero error value on failure and 0 on success.
