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<h1>Db.set_dup_compare</h1>
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<h3><pre>
import com.sleepycat.db.*;
<p>
public interface DbDupCompare
{
public abstract int dup_compare(Db db, Dbt dbt1, Dbt dbt2);
}
public class Db
{
public void set_dup_compare(DbDupCompare dup_compare)
throws DbException;
...
}
</pre></h3>
<h1>Description</h1>
<p>Set the duplicate data item comparison function. The comparison function
is called when it is necessary to compare a data item specified by the
application with a data item currently stored in the tree. The first
argument to the comparison function is the <a href="../../db4-devel-4.0.14/api_java/dbt_class.html">Dbt</a> representing the
application's data item; the second is the current tree's data item.
<p>The comparison function must return an integer value less than, equal
to, or greater than zero if the first data item argument is considered
to be respectively less than, equal to, or greater than the second data
item argument. In addition, the comparison function must cause the data
items in the set to be <i>well-ordered</i>. The comparison function
must correctly handle any data item values used by the application
(possibly including zero-length data items). The <b>data</b> and
<b>size</b> fields of the <a href="../../db4-devel-4.0.14/api_java/dbt_class.html">Dbt</a> are the only fields that may be
used for the purposes of this comparison, and no particular alignment
of the memory to which the <b>data</b> field refers may be assumed.
<p>If no comparison function is specified, the data items are compared
lexically, with shorter data items collating before longer data items.
The same duplicate data item comparison method must be used each time
a particular Btree is opened.
<p>The Db.set_dup_compare interface may be used only to configure Berkeley DB before
the <a href="../../db4-devel-4.0.14/api_java/db_open.html">Db.open</a> interface is called.
<p>The Db.set_dup_compare method throws an exception that encapsulates a non-zero error value on
failure.
<h1>Errors</h1>
<p>The Db.set_dup_compare 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.set_dup_compare 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.set_dup_compare 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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