Question

我有一个用于持久化某些Java对象的MySQL表，并使用Hibernate来映射数据/列。对象/表包含大约50列/字段。在表面和最小负载下，这工作正常，但我在程序启动时遇到问题，我从表中加载所有可用对象。表中目前有大约8500行。加载这些行需要花费很长时间，超过5分钟！显然这是不对的，我必须在我的Hibernate配置（或其他地方）中做了一些可怕的错误。使用java.sql。*包对所有行进行常规查询需要大约300毫秒来检索8000+行，这是可以接受的，但理想情况下我希望保留Hibernate的映射功能。

我已经在下面附加了Hibernate的主要配置。我很乐意提供进一步的配置/实施细节，但我不想在这个阶段用可能不必要的信息来讨论这个问题。

<hibernate-configuration>
<session-factory>
  <property name="hibernate.connection.driver_class">
    com.mysql.jdbc.Driver</property>
  <property name="hibernate.connection.url">

jdbc:mysql://127.0.0.1:3306/abc</property>
  <property name="hibernate.connection.username">user</property>
  <property name="hibernate.connection.password">password</property>

  <property name="org.hibernate.SQL">true</property>
  <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
  <property name="hibernate.hbm2ddl.auto">update</property>

  <property name="hibernate.c3p0.idle_test_period">60</property>
  <property name="hibernate.c3p0.min_size">5</property>
  <property name="hibernate.c3p0.max_size">20</property>
  <property name="hibernate.c3p0.max_statements">250</property>
  <property name="hibernate.c3p0.timeout">1800</property>
  <property name="hibernate.c3p0.acquireRetryAttempts">1</property>
  <property name="hibernate.c3p0.acquireRetryDelay">250</property>

  <property name= "hibernate.transaction.factory_class">
      org.hibernate.transaction.JDBCTransactionFactory
  </property>
  <property name="hibernate.current_session_context_class">thread</property>

我最初使用默认连接池，但尝试切换到C3P0，希望它有所帮助，但无论池如何，行的加载时间基本相同。

显然我不是Hibernate专家，所以我真的很感激我对错误的看法。感谢。

UPDATE1 从查询中添加日志输出。

20:16:40,633 DEBUG QueryTranslatorImpl:283 - --- HQL AST ---
     \-[QUERY] Node: 'query'
        +-[SELECT_FROM] Node: 'SELECT_FROM'
        |  \-[FROM] Node: 'from'
        |     \-[RANGE] Node: 'RANGE'
        |        \-[DOT] Node: '.'
        |           +-[DOT] Node: '.'
        |           |  +-[DOT] Node: '.'
        |           |  |  +-[DOT] Node: '.'
        |           |  |  |  +-[IDENT] Node: 'com'
        |           |  |  |  \-[IDENT] Node: 'xyz'
        |           |  |  \-[IDENT] Node: 'objects'
        |           |  \-[IDENT] Node: 'abc'
        |           \-[IDENT] Node: 'ObjectID'
        \-[WHERE] Node: 'where'
           \-[EQ] Node: '='
              +-[IDENT] Node: 'event_id'
              \-[NUM_INT] Node: '1331570489282'

20:16:40,633 DEBUG QueryTranslatorImpl:252 - --- SQL AST ---
 \-[SELECT] QueryNode: 'SELECT'  querySpaces (order_log)
    +-[SELECT_CLAUSE] SelectClause: '{derived select clause}'
    |  +-[SELECT_EXPR] SelectExpressionImpl: 'objectid0_.event_id as abc1_0_' {FromElement{explicit,not a collection join,not a fetch join,fetch non-lazy properties,classAlias=null,role=null,tableName=order_log,tableAlias=objectid0_,origin=null,columns={,className=com.xyz.objects.abc.objectid}}}
    |  \-[SQL_TOKEN] SqlFragment: 'objectid0_.order_id as abc2_0_, objectid0_.order_id as order3_0_, objectid0_.px_cond as px4_0_, objectid0_.px_curr as px5_0_, objectid0_.px_value as px6_0_, objectid0_.vol_cond as vol7_0_, objectid0_.vol as vol0_, objectid0_.side as side0_, objectid0_.trd_vol as trd10_0_, objectid0_.open_vol as open11_0_, objectid0_.accno as accno0_, objectid0_.symbol as symbol0_, objectid0_.market as market0_, objectid0_.validity_type as validity15_0_, objectid0_.validity_date as validity16_0_, objectid0_.mod_date as mod17_0_, objectid0_.result_code as result18_0_, objectid0_.order_state as order19_0_, objectid0_.action_state as action20_0_, objectid0_.action_type as action21_0_, objectid0_.action_status as action22_0_, objectid0_.status_text as status23_0_, objectid0_.strategy_id as strategy24_0_, objectid0_.passive as passive0_, objectid0_.timestamp as timestamp0_, objectid0_.confirmedorder as confirm27_0_, objectid0_.updatesource as updates28_0_'
    +-[FROM] FromClause: 'from' FromClause{level=1, fromElementCounter=1, fromElements=1, fromElementByClassAlias=[], fromElementByTableAlias=[objectid0_], fromElementsByPath=[], collectionJoinFromElementsByPath=[], impliedElements=[]}
    |  \-[FROM_FRAGMENT] FromElement: 'order_log objectid0_' FromElement{explicit,not a collection join,not a fetch join,fetch non-lazy properties,classAlias=null,role=null,tableName=order_log,tableAlias=objectid0_,origin=null,columns={,className=com.abc.objects.xyz.objectid}}
    \-[WHERE] SqlNode: 'where'
       \-[EQ] BinaryLogicOperatorNode: '='
          +-[IDENT] IdentNode: 'event_id' {originalText=event_id}
          \-[NUM_INT] LiteralNode: '1331570489282'

日志中有更多输出，但我认为上面的两项是最相关的。如果我错过了任何重要的内容，请告诉我。

UPDATE2 添加实际的sql-output。

Hibernate: /* from objectid where abc_event_id=1331570505614 */ select objectid0
_.abc_event_id as abc1_0_, objectid0_.abc_order_id as abc2_0_, objectid0_.
order_id as order3_0_, objectid0_.px_cond as px4_0_, objectid0_.px_curr as px5_0_,
 objectid0_.px_value as px6_0_, objectid0_.vol_cond as vol7_0_, objectid0_.vol as v
ol0_, objectid0_.side as side0_, objectid0_.trd_vol as trd10_0_, objectid0_.open_vo
l as open11_0_, objectid0_.accno as accno0_, objectid0_.symbol as symbol0_, ucorde
r0_.market as market0_, objectid0_.validity_type as validity15_0_, objectid0_.vali
dity_date as validity16_0_, objectid0_.mod_date as mod17_0_, objectid0_.result_cod
e as result18_0_, objectid0_.order_state as order19_0_, objectid0_.action_state as
 action20_0_, objectid0_.action_type as action21_0_, objectid0_.action_status as a
ction22_0_, objectid0_.status_text as status23_0_, objectid0_.strategy_id as strat
egy24_0_, objectid0_.passive as passive0_, objectid0_.timestamp as timestamp0_, uc
order0_.confirmedorder as confirm27_0_, objectid0_.updatesource as updates28_0_ f
rom order_log objectid0_ where abc_event_id=1331570505614

更新3 对象映射+事务代码

<hibernate-mapping>
  <class name="com.abc.objects.xyz.objectid" table="order_log">
   <id name="EventId" type="long" column="event_id" >
   <generator class="assigned"/>
  </id>

  <property name="ordId">
    <column name="order_id"/>
  </property>
  <property name="pxCond">
    <column name="px_cond"/>
  </property>
...
</hibernate-mapping>

映射是摘录，但它与上面的行相同。查询表的事务如下所示：

Session session = HibernateUtil.getSessionFactory().openSession();
org.hibernate.Transaction transaction = null;
try {
   long t0 = System.currentTimeMillis();
   transaction = session.beginTransaction();
   List<UCOrder> result = session.createQuery("from UCOrder").list();
   transaction.commit();
   System.out.println (result.size() + " rows were retrieved");
   System.out.println("Time elapsed: " + (System.currentTimeMillis()-t0));
} catch (Exception e) {
   transaction.rollback();
   e.printStackTrace();
} finally {
   session.close();
}

我还想直截了当地思考？！？但是，与下面说明的vanilla java.sql.*方法相比，检索数据所需的时间是千倍：

Connection conn = DriverManager.getConnection (url, userName, password);
Statement s = conn.createStatement ();
s.executeQuery ("SELECT * FROM order_log");
ResultSet rs = s.getResultSet ();

Answer 1

我建议您在Hibernate中启用详细日志记录。您可以使用它来记录所有SQL查询，并查看它们中是否存在异常。

一种方法是将hibernate.show_sql设置为true和/或（？）配置Hibernate使用的公共日志记录，将所有org.hibernate类别输出到您喜欢的输出文件。< / p>

Answer 2

您不需要在“选择”中进行交易。如果您使用log4j，请禁用hibernate的调试。申请关联表“模式懒惰”。这非常重要。

Java MySQL Hibernate选择慢查询

2 个答案: