聊聊jdbc的batch操作

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本文主要研究一下jdbc的batch的使用以及jpa的batch设置

batch

statement的batch操作,可以批量进行insert或update操作,提升操作性能,特别是在大数据量的insert或update的时候。

使用方式

    @Test
    public void testSqlInjectSafeBatch(){
        String sql = "insert into employee (name, city, phone) values (?, ?, ?)";

        Connection conn = null;
        PreparedStatement pstmt = null;

        try{
            conn = dataSource.getConnection();
            conn.setAutoCommit(false);
            pstmt = conn.prepareStatement(sql);

            for (int i=0;i<3;i++) {
                pstmt.setString(1,"name"+i);
                pstmt.setString(2,"city"+i);
                pstmt.setString(3,"iphone"+i);
                pstmt.addBatch();
            }
            pstmt.executeBatch();

            conn.commit();

        }catch (SQLException e){
            e.printStackTrace();
            try {
                conn.rollback();
            } catch (SQLException e1) {
                e1.printStackTrace();
            }
        }finally {
            DbUtils.closeQuietly(pstmt);
            DbUtils.closeQuietly(conn);
        }
    }
主要就是每条操作参数设置完之后,调用addBatch方法,然后再所有操作都pstmt.addBatch()完之后,调用pstmt.executeBatch()
这种方式有个缺陷就是数据量大容易消耗内存,因此建议再分批次处理
@Test
    public void testSqlInjectSafeAndOOMSafeBatch(){
        String sql = "insert into employee (name, city, phone) values (?, ?, ?)";

        Connection conn = null;
        PreparedStatement pstmt = null;

        final int batchSize = 1000;
        int count = 0;

        try{
            conn = dataSource.getConnection();
            pstmt = conn.prepareStatement(sql);

            for (int i=0;i<10000;i++) {
                pstmt.setString(1,"name"+i);
                pstmt.setString(2,"city"+i);
                pstmt.setString(3,"iphone"+i);
                pstmt.addBatch();

                //小批量提交,避免OOM
                if(++count % batchSize == 0) {
                    pstmt.executeBatch();
                }
            }

            pstmt.executeBatch(); //提交剩余的数据

        }catch (SQLException e){
            e.printStackTrace();
        }finally {
            DbUtils.closeQuietly(pstmt);
            DbUtils.closeQuietly(conn);
        }
    }

jpa的batch设置

spring:
  jpa:
    database-platform: org.hibernate.dialect.PostgreSQLDialect
    hibernate:
      ddl-auto: update
      naming:
        implicit-strategy: org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy
        physical-strategy: org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy
    show-sql: true
    properties:
      hibernate:
        format_sql: true
        jdbc:
          batch_size: 5000
          batch_versioned_data: true
        order_inserts: true
        order_updates: true
通过设置spring.jpa.properties.hibernate.jdbc.batch_size来设置批量

实例测试

    @Test
    public void testJpaBatch() {
        List<DemoUser> demoUsers = new ArrayList<>();
        for(int i=0;i<10;i++){
            DemoUser demoUser = new DemoUser();
            demoUser.setPrincipal("demo");
            demoUser.setAccessToken(UUID.randomUUID().toString());
            demoUser.setAuthType(UUID.randomUUID().toString());
            demoUser.setDeptName(UUID.randomUUID().toString());
            demoUser.setOrgName(UUID.randomUUID().toString());
            demoUsers.add(demoUser);
        }
        StopWatch stopWatch = new StopWatch("jpa batch");
        stopWatch.start();
        demoUserDao.save(demoUsers);
        stopWatch.stop();
        System.out.println(stopWatch.prettyPrint());
    }

调整batch_size参数的测试结果

     没有设置批量
     * StopWatch 'jpa batch': running time (millis) = 21383
     -----------------------------------------
     ms     %     Task name
     -----------------------------------------
     21383  100%

     设置批量500
     StopWatch 'jpa batch': running time (millis) = 16790
     -----------------------------------------
     ms     %     Task name
     -----------------------------------------
     16790  100%

     批量1000
     StopWatch 'jpa batch': running time (millis) = 12317
     -----------------------------------------
     ms     %     Task name
     -----------------------------------------
     12317  100%

     批量5000
     StopWatch 'jpa batch': running time (millis) = 13190
     -----------------------------------------
     ms     %     Task name
     -----------------------------------------
     13190  100%

小结

jdbc的batch参数对于大数据量的新增/更新操作来说,非常有用,可以提升批量操作的效率。

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当一个代码的工匠回首往事时,不因虚度年华而悔恨,也不因碌碌无为而羞愧,这样,当他老的时候,可以很自豪告诉世人,我曾经将代码注入生命去打造互联网的浪潮之巅,那是个很疯狂的时代,我在一波波的浪潮上留下了或重如泰山或轻如鸿毛的几笔。

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