当您需要使用JDBC检索新生成的密钥时，在Oracle（11.2）中实现自动增量功能的最佳方法（在插入性能方面）？
我知道Oracle 12中有标识列，但我现在仍然坚持使用11.2。
和其他许多人一样，我没有把JDBC getGeneratedKeys（）与Oracle一起工作。我最终在我的Oracle（11.2）数据库中触发了一个类似于MySQL自动增量函数的触发器，并且只要有一个插入到该表中，就从表特定序列中插入NextVal作为其主键。这使得新插入的密钥变得困难，我最终做了第二次查询以获得新生成的密钥。
最近我发现了带有返回值的CallableStatement，我看到如何通过1次调用来完成所有操作。
当你还需要新生成的密钥时，这种最后一种方法通常是一种更快速的插入方法吗？或者我有一个更好的选择，我错过了吗？
答案 0 :(得分：1)
我在迷你基准测试中得到了积极的结果并决定分享它。
测试代码：
import org.springframework.jdbc.support.JdbcUtils;
import org.springframework.util.Assert;
import org.springframework.util.StopWatch;
import java.sql.*;
public class TriggerPerformanceTest {
private static final int STEPS_COUNT = 1000;
public static void main(String[] args) throws SQLException {
final Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@host:1521/oradev", "user", "pass");
prepare(connection);
final StopWatch stopWatch = new StopWatch("mini-bench");
testTrigger(connection, stopWatch);
testSequence(connection, stopWatch);
testSeparateCalls(connection, stopWatch);
JdbcUtils.closeConnection(connection);
System.out.println(stopWatch.prettyPrint());
}
private static void testTrigger(Connection connection, StopWatch stopWatch) throws SQLException {
final PreparedStatement preparedStatement = connection.prepareStatement("INSERT INTO test_table_trigger (text) VALUES (?)", new String[]{"ID"});
stopWatch.start("with trigger");
for (int i = 0; i < STEPS_COUNT; i++) {
preparedStatement.setString(1, "test");
preparedStatement.executeUpdate();
final ResultSet resultSet = preparedStatement.getGeneratedKeys();
final boolean next = resultSet.next();
Assert.state(next, "Expected not empty result set with generated keys");
final long id = resultSet.getLong(1);
Assert.state(id > 0, "Expected generated key value");
JdbcUtils.closeResultSet(resultSet);
}
stopWatch.stop();
JdbcUtils.closeStatement(preparedStatement);
}
private static void testSequence(Connection connection, StopWatch stopWatch) throws SQLException {
final PreparedStatement preparedStatement = connection.prepareStatement("INSERT INTO test_table_sequence (id, text) VALUES (sq_test2.NEXTVAL, ?)", new String[]{"ID"});
stopWatch.start("without trigger");
for (int i = 0; i < STEPS_COUNT; i++) {
preparedStatement.setString(1, "test");
preparedStatement.executeUpdate();
final ResultSet resultSet = preparedStatement.getGeneratedKeys();
final boolean next = resultSet.next();
Assert.state(next, "Expected not empty result set with generated keys");
final long id = resultSet.getLong(1);
Assert.state(id > 0, "Expected generated key value");
JdbcUtils.closeResultSet(resultSet);
}
stopWatch.stop();
JdbcUtils.closeStatement(preparedStatement);
}
private static void testSeparateCalls(Connection connection, StopWatch stopWatch) throws SQLException {
final PreparedStatement preparedStatementSeq = connection.prepareStatement("SELECT sq_test3.NEXTVAL FROM dual");
final PreparedStatement preparedStatement = connection.prepareStatement("INSERT INTO test_table_generated (id, text) VALUES (?, ?)");
stopWatch.start("separate calls");
for (int i = 0; i < STEPS_COUNT; i++) {
final ResultSet resultSet = preparedStatementSeq.executeQuery();
resultSet.next();
final long id = resultSet.getLong(1);
JdbcUtils.closeResultSet(resultSet);
preparedStatement.setLong(1, id);
preparedStatement.setString(2, "test");
preparedStatement.executeUpdate();
}
stopWatch.stop();
JdbcUtils.closeStatement(preparedStatementSeq);
JdbcUtils.closeStatement(preparedStatement);
}
private static void prepare(Connection connection) throws SQLException {
Statement statement = connection.createStatement();
try {
statement.execute("DROP TABLE test_table_sequence");
statement.execute("DROP TABLE test_table_trigger");
statement.execute("DROP TABLE test_table_generated");
statement.execute("DROP SEQUENCE sq_test1");
statement.execute("DROP SEQUENCE sq_test2");
statement.execute("DROP SEQUENCE sq_test3");
} catch (SQLException sqle) {
//ignore
}
try {
statement.execute("CREATE TABLE test_table_sequence (id NUMBER, text VARCHAR2(10))");
statement.execute("CREATE TABLE test_table_trigger (id NUMBER, text VARCHAR2(10))");
statement.execute("CREATE TABLE test_table_generated (id NUMBER, text VARCHAR2(10))");
statement.execute("CREATE SEQUENCE sq_test1 START WITH 1 INCREMENT BY 1 CACHE 20");
statement.execute("CREATE SEQUENCE sq_test2 START WITH 1 INCREMENT BY 1 CACHE 20");
statement.execute("CREATE SEQUENCE sq_test3 START WITH 1 INCREMENT BY 1 CACHE 20");
statement.execute("CREATE OR REPLACE TRIGGER trg_increment BEFORE INSERT ON test_table_trigger FOR EACH ROW\n" +
"BEGIN\n" +
" SELECT sq_test1.NEXTVAL INTO :new.id FROM dual;\n" +
"END;");
} catch (SQLException sqle) {
sqle.printStackTrace();
}
try {
statement.execute("TRUNCATE TABLE test_table_sequence");
statement.execute("TRUNCATE TABLE test_table_trigger");
statement.execute("TRUNCATE TABLE test_table_generated");
} catch (SQLException sqle) {
sqle.printStackTrace();
}
}
}
输出：
StopWatch 'mini-bench': running time (millis) = 27430
-----------------------------------------
ms % Task name
-----------------------------------------
09214 034% with trigger
08916 033% without trigger
09300 034% separate calls
结论：差异很小......要考虑到这一点。
PS。专用的Oracle 11.2.0.4，LAN 1Gb / s，Java 1.7.0_65。
答案 1 :(得分：0)
和其他许多人一样，我没有运气让JDBC getGeneratedKeys（）与Oracle一起工作
实际上这很容易。
以下适用于我的触发器和Oracle 11.2和驱动程序版本11.2.0.3.0（以及11.2.0.43.0）
create sequence foo_seq;
create table foo (id integer not null primary key, some_data varchar(20));
触发器：
create trigger foo_trg
before insert on foo
for each row
begin
:new.id := foo_seq.nextval;
end;
/
Java代码：
String insert = "insert into foo (some_data) values (?)";
PreparedStatement pstmt = conection.prepareStatement(insert, new String[]{"ID"});
pstmt.setString(1, "bla");
pstmt.executeUpdate();
ResultSet rs = pstmt.getGeneratedKeys();
while (rs.next()) {
long id = rs.getLong(1);
System.out.println("The generated ID was: " + id);
}
rs.close();
如果由于性能考虑而不想要触发器，如果您更改insert语句以使用序列，则上述代码无需触发器即可运行：
String insert = "insert into foo (id, some_data) values (foo_seq.nextval, ?)";