Oracle-botstrap$--详解.doc

Oracle-bootstrap$--详解 Oracle bootstrap$ 详解Oracle bootstrap$ 详解 一. 官网说明Oracle官方文档对Bootstrap$的说明： UnderstandingBootstrap Of Oracle Database /tianlesoftware/article/details/6823453 In Oracle,Bootstrap refers to loading of metadata (data dictionary) before we OPEN thedatabase. Bootstrap objects are classified as the objects (tables / indexes / clusters) with the object_id below 56 as bootstrap objects. Object_id 在56以下的都作为bootstrap objects，这些对象都是Oracle 的核心对象，这里为什么是56，和Oracle 版本有关系，如果核心对象多，这里的数字就会更大。 在之前的一篇Blog中有说明，10g中X$KCVFH中字段FHRDB对应的就是bootstrap$. 而FHRDB 对应的object id 就是56. 在Oracle11g中，这个bootstrap$对应的就是59. Oracle 10g 中 X$KCVFH 说明 /tianlesoftware/article/details/6919280 These objects are mandatory to bring up an instance, as this contains the most important metadata of the database. 1.1 What happens on database startup?This shall beexplained by setting theSQL_TRACE while opening the database. 用sysdba 执行如下步骤可以查看在数据库OPEN时都有哪些操作： （1）STARTUP MOUNT;（2）ALTER SESSION SET EVENTS ’10046TRACE NAME CONTEXT FOREVER, LEVEL 12′;（3）ALTER DATABASE OPEN;（4）ALTER SESSION SET EVENTS ’10046TRACE NAME CONTEXT OFF’;（5）SHOW PARAMETER USER_DUMP_DEST（6）ORADEBUG SETMYPID（7）ORADEBUG TRACEFILE_NAME 示例： [oracle@dave ~]$ sqlplus / as sysdba; SQL*Plus: Release .0 Production onMon Oct 31 10:13:01 2011 Copyright (c) 1982, 2011, Oracle. All rights reserved. Connected to an idle instance. SQLgt; startup mount; ORACLE instance started. Total System Global Area 1043886080 bytes Fixed Size 2234960 bytes Variable Size 838862256 bytes Database Buffers 197132288 bytes Redo Buffers 5656576 bytes Database mounted. SQLgt; alter session set events 10046 trace name context forever,level 12; Session altered. SQLgt; alter database open; Database altered. SQLgt; alter session set events 10046trace name context off; Session altered. SQLgt; oradebug setmypid Statement processed. SQLgt; oradebug tracefile_name /u01/app/oracle/diag/rdbms/anqing/anqing/trace/anqing_ora_4864.trc Oracle oradebug 命令 使用