如何获取B*Tree索引所在的数据块号

步骤1:找到索引的Object_Id.

SQL> select object_id,object_name from dba_objects where owner='HXL';

 OBJECT_ID OBJECT_NAME
---------- ---------------------------------------------
     51786 IDX_TB_TEST_N1

 

步骤2:Tree Dump

alter session set events 'immediate trace name treedump level 51786'

 

步骤3:找到索引树的首地址

[oracle@hxl udump]$ more oracl_ora_2679.trc
/u01/app/oracle/admin/oracl/udump/oracl_ora_2679.trc
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
ORACLE_HOME = /u01/app/oracle/product/10.2.0/db_1
System name:    Linux
Node name:      hxl
Release:        2.6.9-42.0.0.0.1.ELhugemem
Version:        #1 SMP Sun Oct 15 14:06:18 PDT 2006
Machine:        i686
Instance name: oracl
Redo thread mounted by this instance: 1
Oracle process number: 18
Unix process pid: 2679, image: (TNS V1-V3)

*** 2012-01-04 18:23:29.845
*** SERVICE NAME:(SYS$USERS) 2012-01-04 18:23:29.791
*** SESSION ID:(144.20) 2012-01-04 18:23:29.789
----- begin tree dump
branch: 0x1400494 20972692 (0: nrow: 2, level: 1)
   leaf: 0x1400497 20972695 (-1: nrow: 540 rrow: 540)
   leaf: 0x1400498 20972696 (0: nrow: 23 rrow: 23)
----- end tree dump
*** 2012-01-04 18:27:52.766
*** 2012-01-04 18:27:52.765 60679 kcrr.c
ARCH: Archival disabled due to shutdown: 1089
*** 2012-01-04 18:27:53.904 60679 kcrr.c
ARCH: Archival disabled due to shutdown: 1089

 

步骤4:通过首地址获取索引所在的快号

SELECT dbms_utility.data_block_address_file(to_number(ltrim('0x1400494',
                                                            '0x'),
                                                      'xxxxxxxx')) file#,
       dbms_utility.data_block_address_block(to_number(ltrim('0x1400494',
                                                             '0x'),
                                                       'xxxxxxxx')) block#
      FROM dual;

     FILE#     BLOCK#
---------- ----------
         5       1172

 

这里1172就是索引IDX_TB_TEST_N1所占用的起始数据块号.