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<title>Berkeley DB: Db.sync</title>
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<h1>Db.sync</h1>
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<h3><pre>
import com.sleepycat.db.*;
<p>
public int sync(int flags)
throws DbException;
</pre></h3>
<h1>Description</h1>
<p>The Db.sync method flushes any cached information to disk.
<p>If the database is in memory only, the Db.sync method has no effect and
will always succeed.
<p>The <b>flags</b> parameter is currently unused, and must be set to 0.
<p><b>It is important to understand that flushing cached information to disk
only minimizes the window of opportunity for corrupted data.</b> Although
unlikely, it is possible for database corruption to happen if a system
or application crash occurs while writing data to the database. To
ensure that database corruption never occurs, applications must either:
use transactions and logging with automatic recovery; use logging and
application-specific recovery; or edit a copy of the database, and once
all applications using the database have successfully called
<a href="../../db4-devel-4.0.14/api_java/db_close.html">Db.close</a>, atomically replace the original database with the
updated copy.
<p>The Db.sync method throws an exception that encapsulates a non-zero error value on
failure, and returns <a href="../../db4-devel-4.0.14/api_c/memp_fsync.html#DB_INCOMPLETE">Db.DB_INCOMPLETE</a> if the underlying database still has
dirty pages in the cache. (The only reason to return
<a href="../../db4-devel-4.0.14/api_c/memp_fsync.html#DB_INCOMPLETE">Db.DB_INCOMPLETE</a> is if another thread of control was writing pages
in the underlying database file at the same time as the
Db.sync method was being called. For this reason, a return of
<a href="../../db4-devel-4.0.14/api_c/memp_fsync.html#DB_INCOMPLETE">Db.DB_INCOMPLETE</a> can normally be ignored; or, in cases where it is
a possible return value, there may be no reason to call
Db.sync.)
<h1>Errors</h1>
<p>The Db.sync method may fail and throw an exception encapsulating a non-zero error for the following conditions:
<p><dl compact>
<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
</dl>
<p>The Db.sync method may fail and throw an exception for errors specified for other Berkeley DB and C library or system methods.
If a catastrophic error has occurred, the Db.sync method may fail and throw
a <a href="../../db4-devel-4.0.14/api_java/runrec_class.html">DbRunRecoveryException</a>, in which case all subsequent Berkeley DB calls
will fail in the same way.
<h1>Class</h1>
<a href="../../db4-devel-4.0.14/api_java/db_class.html">Db</a>
<h1>See Also</h1>
<a href="../../db4-devel-4.0.14/api_java/db_associate.html">Db.associate</a>,
<a href="../../db4-devel-4.0.14/api_java/db_close.html">Db.close</a>,
<a href="../../db4-devel-4.0.14/api_java/db_cursor.html">Db.cursor</a>,
<a href="../../db4-devel-4.0.14/api_java/db_del.html">Db.del</a>,
<a href="../../db4-devel-4.0.14/api_java/db_fd.html">Db.fd</a>,
<a href="../../db4-devel-4.0.14/api_java/db_get.html">Db.get</a>,
<a href="../../db4-devel-4.0.14/api_java/db_get.html">Db.pget</a>,
<a href="../../db4-devel-4.0.14/api_java/db_get_byteswapped.html">Db.get_byteswapped</a>,
<a href="../../db4-devel-4.0.14/api_java/db_get_type.html">Db.get_type</a>,
<a href="../../db4-devel-4.0.14/api_java/db_join.html">Db.join</a>,
<a href="../../db4-devel-4.0.14/api_java/db_key_range.html">Db.key_range</a>,
<a href="../../db4-devel-4.0.14/api_java/db_open.html">Db.open</a>,
<a href="../../db4-devel-4.0.14/api_java/db_put.html">Db.put</a>,
<a href="../../db4-devel-4.0.14/api_java/db_remove.html">Db.remove</a>,
<a href="../../db4-devel-4.0.14/api_java/db_rename.html">Db.rename</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_append_recno.html">Db.set_append_recno</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_bt_minkey.html">Db.set_bt_minkey</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_cachesize.html">Db.set_cachesize</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_errcall.html">Db.set_errcall</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_errpfx.html">Db.set_errpfx</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_feedback.html">Db.set_feedback</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_flags.html">Db.set_flags</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_h_ffactor.html">Db.set_h_ffactor</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_h_nelem.html">Db.set_h_nelem</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_lorder.html">Db.set_lorder</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_pagesize.html">Db.set_pagesize</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_q_extentsize.html">Db.set_q_extentsize</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_re_delim.html">Db.set_re_delim</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_re_len.html">Db.set_re_len</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_re_pad.html">Db.set_re_pad</a>,
<a href="../../db4-devel-4.0.14/api_java/db_set_re_source.html">Db.set_re_source</a>,
<a href="../../db4-devel-4.0.14/api_java/db_stat.html">Db.stat</a>,
<a href="../../db4-devel-4.0.14/api_java/db_sync.html">Db.sync</a>,
<a href="../../db4-devel-4.0.14/api_java/db_truncate.html">Db.truncate</a>,
<a href="../../db4-devel-4.0.14/api_java/db_upgrade.html">Db.upgrade</a>,
and
<a href="../../db4-devel-4.0.14/api_java/db_verify.html">Db.verify</a>.
</tt>
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