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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
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* KIND, either express or implied. See the License for the
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package org.apache.cayenne.dba.derby;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Collections;
import org.apache.cayenne.CayenneException;
import org.apache.cayenne.access.DataNode;
import org.apache.cayenne.dba.JdbcAdapter;
import org.apache.cayenne.dba.JdbcPkGenerator;
import org.apache.cayenne.log.JdbcEventLogger;
import org.apache.cayenne.map.DbEntity;
/**
* Default PK generator for Derby that uses updateable ResultSet to get the next id from
* the lookup table.
*
* @since 1.2
*/
public class DerbyPkGenerator extends JdbcPkGenerator {
DerbyPkGenerator(JdbcAdapter adapter) {
super(adapter);
}
static final String SELECT_QUERY = "SELECT NEXT_ID FROM AUTO_PK_SUPPORT"
+ " WHERE TABLE_NAME = ? FOR UPDATE";
/**
* @since 3.0
*/
@Override
protected long longPkFromDatabase(DataNode node, DbEntity entity) throws Exception {
JdbcEventLogger logger = adapter.getJdbcEventLogger();
if (logger.isLoggable()) {
logger.logQuery(SELECT_QUERY, Collections
.singletonList(entity.getName()));
}
Connection c = node.getDataSource().getConnection();
try {
PreparedStatement select = c.prepareStatement(
SELECT_QUERY,
ResultSet.TYPE_FORWARD_ONLY,
ResultSet.CONCUR_UPDATABLE);
try {
select.setString(1, entity.getName());
ResultSet rs = select.executeQuery();
try {
if (!rs.next()) {
throw new CayenneException("PK lookup failed for table: "
+ entity.getName());
}
long nextId = rs.getLong(1);
rs.updateLong(1, nextId + pkCacheSize);
rs.updateRow();
if (rs.next()) {
throw new CayenneException("More than one PK record for table: "
+ entity.getName());
}
c.commit();
return nextId;
}
finally {
rs.close();
}
}
finally {
select.close();
}
}
finally {
c.close();
}
}
}