Question

我正在使用带有一组参数的JDBC Prepared Statement，使用setString（pos，value）。表中的基础列都是NCHAR和NVARCHAR2。我已经设置了Oracle JDBC驱动程序＆＃34; defaultNChar = true＆＃34;以便Oracle DB始终将我的参数视为国家语言字符。驱动程序文件是＆＃34; ojdbc6.jar＆＃34;。

我的问题：我的参数化查询非常慢，＆＃34; defaultNChar = true＆＃34; 。但是一旦我设置＆＃34; defaultNChar = false＆＃34;查询超快（3秒）。

查询用法如下：

String sql = "INSERT INTO MYTABLE_ERROR(MY_NAME,MY_FLAG,MY_VALUE) "
                        + "SELECT ? AS MY_NAME,"
                        + "? AS MY_FLAG,v.MY_VALUE"
                        + " FROM OTHER_TABLE v"
                        + " JOIN ( SELECT * FROM ... iv ... WHERE iv.MY_NAME = ? ) rule1 "
                        + " ON v.\"MY_NAME\"=rule1.\"MY_NAME\" AND v.\"MY_VALUE\"=rule1.\"MY_VALUE\""
                        + " WHERE rule1.\"MY_NAME\" = ? AND v.\"MY_VALUE\" = ?";

preStatement = conn.prepareStatement (sql);
int count = 1;
for (String p : params)
{
        // SLOW
        //preStatement.setNString (count++, p);
        // SLOW
        //preStatement.setObject (count++, p, Types.NVARCHAR);
        // SLOW
        preStatement.setString (count++, p);
}

我一直在努力找到为什么我准备好的语句针对＆＃34; Oracle数据库11g版本11.2.0.3.0 - 64位生产＆＃34;执行的根本原因。使用JDBC驱动程序＆＃34; Oracle JDBC驱动程序，11.2.0.3.0和＃34;，DB速度很慢。我找不到任何线索！

我甚至得到了数据库NLS配置希望找到任何东西，但我不确定这里：

NLS_LANGUAGE    AMERICAN
NLS_TERRITORY   AMERICA
NLS_CURRENCY    $
NLS_ISO_CURRENCY    AMERICA
NLS_NUMERIC_CHARACTERS  .,
NLS_CALENDAR    GREGORIAN
NLS_DATE_FORMAT DD-MON-RR
NLS_DATE_LANGUAGE   AMERICAN
NLS_CHARACTERSET    AL32UTF8
NLS_SORT    BINARY
NLS_TIME_FORMAT HH.MI.SSXFF AM
NLS_TIMESTAMP_FORMAT    DD-MON-RR HH.MI.SSXFF AM
NLS_TIME_TZ_FORMAT  HH.MI.SSXFF AM TZR
NLS_TIMESTAMP_TZ_FORMAT DD-MON-RR HH.MI.SSXFF AM TZR
NLS_DUAL_CURRENCY   $
NLS_NCHAR_CHARACTERSET  AL16UTF16
NLS_COMP    BINARY

请帮忙！

谢谢， -G。

更新：在使用＆＃34; defaultNChar = true＆＃34;时，看起来查询卡住了。不知何故。我在使用JConsole时看到了这个：

Total blocked: 1  Total waited: 1

Stack trace: 
java.net.SocketInputStream.socketRead0(Native Method)
java.net.SocketInputStream.read(Unknown Source)
java.net.SocketInputStream.read(Unknown Source)
oracle.net.ns.Packet.receive(Packet.java:311)
oracle.net.ns.DataPacket.receive(DataPacket.java:103)
oracle.net.ns.NetInputStream.getNextPacket(NetInputStream.java:312)
oracle.net.ns.NetInputStream.read(NetInputStream.java:257)
oracle.net.ns.NetInputStream.read(NetInputStream.java:182)
oracle.net.ns.NetInputStream.read(NetInputStream.java:99)
oracle.jdbc.driver.T4CSocketInputStreamWrapper.readNextPacket(T4CSocketInputStreamWrapper.java:121)
oracle.jdbc.driver.T4CSocketInputStreamWrapper.read(T4CSocketInputStreamWrapper.java:77)
oracle.jdbc.driver.T4CMAREngine.unmarshalUB1(T4CMAREngine.java:1173)
oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:309)
oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:200)
oracle.jdbc.driver.T4C8Oall.doOALL(T4C8Oall.java:543)
oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:238)
oracle.jdbc.driver.T4CPreparedStatement.executeForRows(T4CPreparedStatement.java:1446)
oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1757)
oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:4372)
oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:4539)
   - locked oracle.jdbc.driver.T4CConnection@7f2315e5
oracle.jdbc.driver.OraclePreparedStatementWrapper.executeUpdate(OraclePreparedStatementWrapper.java:5577)
com.mycompany.test.DriverTest.fireStatement(DriverTest.java:253)

Answer 1

您可以使用PreparedStatement.setFormOfUse解决性能问题：

但是，如果将defaultNChar设置为true，然后访问CHAR列，那么数据库将隐式地将所有CHAR数据转换为NCHAR。这种转换会对性能产生重大影响。为了避免这种情况，为每个CHAR调用setFormOfUse（4，OraclePreparedStatement.FORM_CHAR）声明中提到的列。例如：
    PreparedStatement pstmt =
    conn.prepareStatement("insert into TEST values(?,?,?)");
    pstmt.setInt(1, 1); // NUMBER column
    pstmt.setString(2, myUnicodeString1); // NVARCHAR2 column
    pstmt.setString(3, myUnicodeString2); // NCHAR column
    pstmt.setFormOfUse(4, OraclePreparedStatement.FORM_CHAR);
    pstmt.setString(4, myString); // CHAR column
    pstmt.execute();

https://docs.oracle.com/cd/B19306_01/java.102/b14355/global.htm#CHDHHJDB

在NCHAR / NVARCHAR2上，Oracle defaultNChar = true SLOW

1 个答案: