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我正在尝试通过休眠查询来衡量数据获取时间的性能。为了这 ：-

a.) 我打开了两个不同的会话，并且在两个会话中，我都使用了相同的 Hibernate 查询。

b.) 在 Session1 中，所用时间为 162 毫秒，在 Session2 中获取数据时，所用时间为 24 毫秒。

为什么查询执行时间会有这种差异？根据逻辑理解，每次（在不同的会话中），都会有一个新的查询被命中......所以，查询执行时间也应该是相似的。？？？

注意：- 此测试程序中没有启用二级缓存。

会话会话 = HibernateUtil.getSessionFactory().openSession(); VendorDaoImpl vendorDao = new VendorDaoImpl();

        long start = System.currentTimeMillis(); 
        VendorDetail vendorDetailRecord1 = vendorDao.getVendorByCode(session, "92f880");
        long end = System.currentTimeMillis(); 
        System.out.println("Time to fetch from DB while in Session 1:  " + (end-start));

        session.close();

        Session session2 = HibernateUtil.getSessionFactory().openSession();

        start = System.currentTimeMillis();     
        VendorDetail vendorDetailRecord2 = vendorDao.getVendorByCode(session2, "92f880");
        end = System.currentTimeMillis(); 
        System.out.println("Time to fetch from DB while in session 2:  " + (end-start));

        session2.close();

以下是结果：-

Hibernate：选择 vendordeta0_.id 作为 id0_0_，vendordeta0_.banned_zip_pattern 作为banned2_0_0_，vendordeta0_.code 作为code0_0_，vendordeta0_.company_name 作为company4_0_0_，vendordeta0_.created 作为created0_0_，vendordeta0_.cst_number 作为cst6_0_0_，vendordeta0_.default_page 作为default7_0000 启用, vendordeta0_.max_invoice_number as max9_0_0_, vendordeta0_.name as name0_0_, vendordeta0_.next_invoice_number_reset_date as next11_0_0_, vendordeta0_.print_mock_invoice as print12_0_0_, vendordeta0_.special_panel_access as special13_0_0_, vendordeta0_.starting_invoice_number as starting14_0_0_, vendordeta0_.tin_number as tin15_0_0_, vendordeta0_.updated as updated0_0_, vendordeta0_ .version as version0_0_ from test.vendor_detail vendordeta0_ where vendordeta0_.code=?

在会话 1 中从数据库获取的时间：162

Hibernate：选择 vendordeta0_.id 作为 id0_0_，vendordeta0_.banned_zip_pattern 作为banned2_0_0_，vendordeta0_.code 作为code0_0_，vendordeta0_.company_name 作为company4_0_0_，vendordeta0_.created 作为created0_0_，vendordeta0_.cst_number 作为cst6_0_0_，vendordeta0_.default_page 作为default7_0000 启用, vendordeta0_.max_invoice_number as max9_0_0_, vendordeta0_.name as name0_0_, vendordeta0_.next_invoice_number_reset_date as next11_0_0_, vendordeta0_.print_mock_invoice as print12_0_0_, vendordeta0_.special_panel_access as special13_0_0_, vendordeta0_.starting_invoice_number as starting14_0_0_, vendordeta0_.tin_number as tin15_0_0_, vendordeta0_.updated as updated0_0_, vendordeta0_ .version as version0_0_ from test.vendor_detail vendordeta0_ where vendordeta0_.code=?

在会话 2 中从数据库获取的时间：24

任何帮助将不胜感激！

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