Oracle数据块结构剖析

一. 构造测试数据

SQL> create table t1(id int,name varchar2(100));

Table created.

SQL> insert into t1 values(1,'AAAAA');

1 row created.

SQL> commit;

Commit complete.

SQL> alter system checkpoint; # 手工检查点，确保数据写入数据文件

System altered.

二. dump数据块

SQL> select  id,name,dbms_rowid.rowid_relative_fno(rowid) file#,dbms_rowid.rowid_block_number(rowid) block# from t1;

        ID NAME            FILE#     BLOCK#
---------- ---------- ---------- ----------
         1 AAAAA               6        135

SQL> alter system dump datafile 6 block 135;

System altered.

三. dump内容分析

1. 数据块头

Block dump from disk:
buffer tsn: 8 rdba: 0x01800087 (6/135)
scn: 0x0000.002f030e seq: 0x01 flg: 0x06 tail: 0x030e0601
frmt: 0x02 chkval: 0x816d type: 0x