SQL> conn xh/a831115
Connected.

SQL> create table t1 (a int,b varchar2(10)) pctfree 0 initrans 1;

Table created.

SQL> SQL>  declare
  2      begin
    for i in 1..1000 loop
  3    4      insert into t1 values(i,'a');
  5      end loop;
  6      commit;
  7      end;
  8  /

PL/SQL procedure successfully completed.

SQL> execute dbms_stats.gather_table_stats('xh','t1');

PL/SQL procedure successfully completed.

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

    BLOCK#
----------
      3639
      3640

SQL> select pct_free,pct_used,ini_trans from user_tables where table_name='T1';

  PCT_FREE   PCT_USED  INI_TRANS
---------- ---------- ----------
         0                     1
SQL> update t1 set b='aa' where a=1;

1 row updated.

SQL> update t1 set b='aaa' where a=2;

1 row updated.

SQL> select distinct sid from v$mystat;

       SID
----------
       128

SQL> update t1 set b='aaaa' where a=3;

SQL> select event from v$session where sid=128;

EVENT
----------------------------------------------------------------              TX MODE =4
enq: TX - allocate ITL entry

SQL>

SQL> alter system dump datafile 4  block 3639;

System altered.

SQL> SELECT value FROM v$diag_info WHERE name = 'Default Trace File';

VALUE
--------------------------------------------------------------------------------
/home/oracle/diag/rdbms/xh/xh/trace/xh_ora_4290.trc

 seg/obj: 0x115e6  csc: 0x00.2fadfd  itc: 2  flg: E  typ: 1 - DATA
     brn: 0  bdba: 0x1000e31 ver: 0x01 opc: 0
     inc: 0  exflg: 0
 
 Itl           Xid                  Uba         Flag  Lck        Scn/Fsc
0x01   0x0008.020.00000339  0x00c00515.0272.6e  C---    0  scn 0x0000.002fad58
0x02   0x0004.00f.000002ec  0x00c013a2.027c.2b  ----    1  fsc 0x0000.00000000
bdba: 0x01000e37

SQL> variable file# number;
SQL> variable blk# number;

SQL>  execute :file#:=dbms_utility.data_block_address_file(to_number('1000e37','xxxxxxxxxx'));

PL/SQL procedure successfully completed.

SQL>  execute :blk#:=dbms_utility.data_block_address_block(to_number('1000e37','xxxxxxxxx'));

PL/SQL procedure successfully completed.

SQL> print file#

     FILE#
----------
         4

SQL> print blk#

      BLK#
----------
      3639

 Flag :标记共4位c---表示已经提交,----表示未提交

flag:--u-表示用户已经提交,之后 如果与该块有关的事务再提交 则 这个itl flag变为c---,以前c---的变为----

关于块中itl

SQL> create table t2 (a int, b int);

表已创建。
  1  declare
  2  begin
  3  for i in 1..20 loop
  4  insert into t2 values(i,i+1);
  5  end loop;
  6  commit;
  7* end;
SQL> /

PL/SQL 过程已成功完成。

SQL> select distinct block# from (select dbms_rowid.rowid_relative_fno(rowid) fi
le#,dbms_rowid.rowid_block_number(rowid) block# from xh.t2);

    BLOCK#
----------
      2632

SQL>

SQL> update xh.t2  set b=23 where a=1;

已更新 1 行。

SQL>  update xh.t2  set b=24 where a=2;

已更新 1 行。

SQL> update xh.t2 set b=25 where a=3;

已更新 1 行。

SQL> alter system dump datafile 4 block 2632;

 Itl           Xid                  Uba         Flag  Lck        Scn/Fsc
0x01   0x000a.002.000004b1  0x00800989.04b0.06  ----    1  fsc 0x0000.00000000
0x02   0x0006.028.00000604  0x00800a20.03fc.26  ----    1  fsc 0x0000.00000000
0x03   0x0008.00f.000005e5  0x00800093.058f.20  ----    1  fsc 0x0000.00000000
3个不同的session更新 产生3个 事务 且都未提交oracle会自动扩展itl

SQL> select max_trans from all_tables where table_name='T2';

 MAX_TRANS
----------
       255
最多可以扩展到255个itl ，可以 扩展但会对性能有影响，可以建表时指定 多个 create table name (id number) initrans 3;

SQL> create table t2 (a int ) initrans 3;

表已创建。

SQL> insert into t2 values(1);

已创建 1 行。

SQL> commit;

提交完成。

SQL> select file#,block# from (select dbms_rowid.rowid_relative_fno(rowid) file#
,dbms_rowid.rowid_block_number(rowid) block# from t2);

     FILE#     BLOCK#
---------- ----------
         1      64554

SQL> alter system dump datafile 1 block 64554;

系统已更改。
 Itl           Xid                  Uba         Flag  Lck        Scn/Fsc
0x01   0x0003.027.000005f5  0x00800aba.0388.34  --U-    1  fsc 0x0000.0053d9b9
0x02   0x0000.000.00000000  0x00000000.0000.00  ----    0  fsc 0x0000.00000000
0x03   0x0000.000.00000000  0x00000000.0000.00  ----    0  fsc 0x0000.00000000