Java MySQL Hibernate緩慢選擇查詢

Question

我有一個MySQL表，用於持久化一些Java對象並使用Hibernate來映射數據/列。對象/表格包含大約50列/字段。在表面上，並在最小的負載下這工作正常，但我遇到了程序啓動時的問題，我從表中加載所有可用的對象。表中目前大約有8500行。加載這些行需要很長的時間，超過5分鐘！顯然這是不對的，我必須在我的Hibernate配置（或其他地方）做一些可怕的錯誤。對於使用java.sql。*包的所有行的普通查詢大約需要300 ms來檢索8000多行，這是可以接受的，但理想情況下，我希望保留Hibernate的映射功能。

我在下面附加了Hibernate的主要配置。我很樂意提供進一步的配置/實現細節，但我不想在這個階段用什麼可能是不必要的信息來膨脹這個問題。

<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> 

我最初使用默認的連接池，而是嘗試切換到C3P0在希望它能幫助，但無論池行的加載時間基本相同。

很顯然，我不是一個Hibernate專家，所以我真的很感謝一些見解，我做錯了什麼。謝謝。

UPDATE1 從查詢中添加日誌輸出。

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' 

在日誌中有很多輸出，但我認爲上面的2個項目是最相關的。如果我錯過了重要的事情，請告訴我。

UPDATE2添加實際的sql輸出。

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 

UPDATE 3對象映射+事務代碼

<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> 

映射是摘錄，但它是直線前進沿着相同的路線如上。查詢表的交易如下所示：

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(); 
} 

也很直截了當我想想？！？。然而，它需要檢索數據的時間千倍相比，如下圖所示香草java.sql.*方法：

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

Answer 1

，我建議你在Hibernate的一個詳細日誌記錄開關。你可以得到它來記錄所有的SQL查詢，看看它們中是否有不尋常的東西。要做到這一點

一種方法是設置hibernate.show_sql到true和/或（？）配置Hibernate使用的輸出所有org.hibernate類你喜歡的輸出文件共享記錄。

Answer 2

您不需要在「選擇」中進行交易。 如果您使用log4j，請禁用對休眠的調試。 申請關聯表「模式懶惰」。這個非常重要。