有人可以解释为什么我从访问 z/os DB2 的 java JDBC 中看到这种行为吗
我有一个包含三列的 z/os db2 v10 表，两列组成 uniue 索引，第三列是一个 pureXML 列，它包含一个长度为 1KByte 的 xml 文档。
该表有 100 万行。每一行都有相同的 xml 文档用于测试目的。
当我运行一个对表进行 10,000 次随机读取的循环时，每次读取总是会找到一行，我的 jdbc 跟踪文件中显示的 db2 服务器时间在 2ms 和 62,000ms 之间变化
什么会导致如此广泛的响应时间？
还有为什么我的 jdbc 跟踪对核心和网络有负时间？
[jcc][SystemMonitor:start]
[jcc][Time:2012-08-02-11:43:48.188][Thread:main][PreparedStatement@10b4b2f] executeQuery () called
[jcc][Time:2012-08-02-11:43:48.219][Thread:main][PreparedStatement@10b4b2f] executeQuery () returned com.ibm.db2.jcc.t4.j@812862
[jcc][SystemMonitor:stop] core: 22.185222ms | network: 21.831545ms | server: 2.956ms
[jcc][Time:2012-08-02-11:44:23.251][Thread:main][PreparedStatement@10b4b2f] executeQuery () called
[jcc][Time:2012-08-02-11:45:25.251][Thread:main][PreparedStatement@10b4b2f] executeQuery () returned com.ibm.db2.jcc.t4.j@68ef48
[jcc][SystemMonitor:stop] core: -3615.90705ms | network: -3616.401806ms | server: 61978.244ms
这是 java/jdbc 环境详细信息
[jcc] Driver: IBM Data Server Driver for JDBC and SQLJ 4.12.79
[jcc] Compatible JRE versions: { 1.6 }
[jcc] Target server licensing restrictions: { z/OS: enabled; SQLDS: enabled; iSeries: enabled; DB2 for Unix/Windows: enabled; Cloudscape: enabled; Informix: enabled }
[jcc] Range checking enabled: true
[jcc] Bug check level: 0xff
[jcc] Default fetch size: 64
[jcc] Default isolation: 2
[jcc] Collect performance statistics: false
[jcc] No security manager detected.
[jcc] Access to package sun.io is permitted by security manager.
[jcc] JDBC 1 system property jdbc.drivers = null
[jcc] Java Runtime Environment version 1.6.0_21
[jcc] Java Runtime Environment vendor = Sun Microsystems Inc.
[jcc] Java vendor URL = http://java.sun.com/
[jcc] Java installation directory = C:\Program Files\Java\jre6
[jcc] Java Virtual Machine specification version = 1.0
[jcc] Java Virtual Machine specification vendor = Sun Microsystems Inc.
[jcc] Java Virtual Machine specification name = Java Virtual Machine Specification
[jcc] Java Virtual Machine implementation version = 17.0-b17
[jcc] Java Virtual Machine implementation vendor = Sun Microsystems Inc.
[jcc] Java Virtual Machine implementation name = Java HotSpot(TM) Client VM
[jcc] Java Runtime Environment specification version = 1.6
[jcc] Java Runtime Environment specification vendor = Sun Microsystems Inc.
[jcc] Java Runtime Environment specification name = Java Platform API Specification
[jcc] Java class format version number = 50.0
[jcc] Operating system name = Windows XP
[jcc] Operating system architecture = x86
[jcc] Operating system version = 5.1
[jcc] File separator ("/" on UNIX) = \
[jcc] Path separator (":" on UNIX) = ;
[jcc] Dumping all file properties: { }
[jcc] pureQuery present = false
Database product name: DB2
Database product version: DSN10015
Driver name: IBM Data Server Driver for JDBC and SQLJ
Driver version: 4.12.79