• 非IMU模式下DML语句产生的REDO日志内容格式解读


    实验内容:非IMU模式下DML语句产生的REDO日志内容格式解读
    最详细的解读是UPDATE的。

    实验环境准备

    11G中默认是开启IMU特性的,做此实验需要关闭此特性。
    alter system set "_in_memory_undo"=false;
    alter system set "_in_memory_undo"=true;  --实验结束后使用此语句改回使用IMU特性。
    修改参数完成后,重启数据库:
    shutdown immediate;
    startup;
    准备好实验用的表----BYS.DEPT表。
    SYS@ bys3>select object_id from dba_objects where object_name='DEPT';
     OBJECT_ID
    ----------
         22327
    SYS@ bys3>select * from bys.dept;
        DEPTNO DNAME          LOC
    ---------- -------------- -------------
            10 ACCOUNTING     NEW YORK
            20 RESEARCH       DALLAS
            40 OPERATIONS     BOSTON
            11 chedan         bj
            22 test           sh       
    BYS@ bys3>col file_name for a35
    SYS@ bys3>col name for a15
    SYS@ bys3> select a.file_id,b.ts#,b.name,a.file_name from dba_data_files a,v$tablespace b where a.TABLESPACE_NAME=b.name;
       FILE_ID        TS# NAME            FILE_NAME
    ---------- ---------- --------------- -----------------------------------
             1          0 SYSTEM          /u01/oradata/bys3/system01.dbf
             2          1 SYSAUX          /u01/oradata/bys3/sysaux01.dbf
             3          2 UNDOTBS1        /u01/oradata/bys3/undotbs01.dbf
             4          4 USERS           /u01/oradata/bys3/user01.dbf
    ###################################################
    开始实验分三步,分别是插入、更新、删除语句的操作。 最详细的解读是UPDATE的。

    实验一:insert 操作的REDO日志解读

    会话1: --SYS用户切换日志并查出当前日志名:
    SYS@ bys3>alter system switch logfile;
    System altered.
    col  MEMBER for a30
    SYS@ bys3>select a.group#,a.sequence#,a.archived,a.status,b.type,b.member from v$log a,v$logfile b where a.group#=b.group#;
        GROUP#  SEQUENCE# ARC STATUS           TYPE    MEMBER
    ---------- ---------- --- ---------------- ------- ------------------------------
             1        310 NO  CURRENT          ONLINE  /u01/oradata/bys3/redo01.log
             2        308 YES INACTIVE         ONLINE  /u01/oradata/bys3/redo02.log
             3        309 YES ACTIVE           ONLINE  /u01/oradata/bys3/redo03.log
    普通用户做插入语句:
    SYS@ bys3>conn bys/bys
    select * from dept;
    Connected.
    BYS@ bys3>
        DEPTNO DNAME          LOC
    ---------- -------------- -------------
            10 ACCOUNTING     NEW YORK
            20 RESEARCH       DALLAS
            40 OPERATIONS     BOSTON
            11 chedan         bj
            22 test           sh
    BYS@ bys3>set time on
    20:34:07 BYS@ bys3>insert into dept values(33,'imutest','hz');
    1 row created.
    20:34:12 BYS@ bys3>commit;
    Commit complete.

    会话2:DUMP当前REDO日志:

    SYS@ bys3>alter system dump logfile '/u01/oradata/bys3/redo01.log';
    System altered.
    SYS@ bys3>select value from v$diag_info where name like 'De%' ;
    VALUE
    ----------------------------------------------------------------------------------------------------
    /u01/diag/rdbms/bys3/bys3/trace/bys3_ora_29063.trc
    ######################
    查看此TRACE文件: 方法是:vi /u01/diag/rdbms/bys3/bys3/trace/bys3_ora_29063.trc 然后搜索修改的对象的OBJECT_ID--     22327
    详解参考下一步的UPDATE的REDO讲解。
    REDO RECORD - Thread:1 RBA: 0x000136.0000000d.0010 LEN: 0x01a0 VLD: 0x05
    SCN: 0x0000.00702f08 SUBSCN:  1 01/06/2014 20:34:13
    (LWN RBA: 0x000136.0000000d.0010 LEN: 0002 NST: 0001 SCN: 0x0000.00702f08)
    CHANGE #1 TYP:0 CLS:21 AFN:3 DBA:0x00c000a0 OBJ:4294967295 SCN:0x0000.00702eda SEQ:1 OP:5.2 ENC:0 RBL:0
    ktudh redo: slt: 0x0003 sqn: 0x00000eaa flg: 0x0012 siz: 112 fbi: 0
                uba: 0x00c01ac7.0250.25    pxid:  0x0000.000.00000000
    CHANGE #2 TYP:0 CLS:22 AFN:3 DBA:0x00c01ac7 OBJ:4294967295 SCN:0x0000.00702ed9 SEQ:3 OP:5.1 ENC:0 RBL:0
    ktudb redo: siz: 112 spc: 3494 flg: 0x0012 seq: 0x0250 rec: 0x25
                xid:  0x0003.003.00000eaa
    ktubl redo: slt: 3 rci: 0 opc: 11.1 [ objn: 22327 objd: 22327 tsn: 4]    ------- tsn: 4插入的这个是在表空间号为4-- OBJ:22327--是插入的对象的OBJECT_ID
    Undo type:  Regular undo        Begin trans    Last buffer split:  No
    Temp Object:  No
    Tablespace Undo:  No
                 0x00000000  prev ctl uba: 0x00c01ac7.0250.22
    prev ctl max cmt scn:  0x0000.007029ac  prev tx cmt scn:  0x0000.007029d6
    txn start scn:  0xffff.ffffffff  logon user: 32  prev brb: 12589763  prev bcl: 0 BuExt idx: 0 flg2: 0
    KDO undo record:
    KTB Redo
    op: 0x03  ver: 0x01
    compat bit: 4 (post-11) padding: 1
    op: Z
    KDO Op code: DRP row dependencies Disabled
      xtype: XA flags: 0x00000000  bdba: 0x010000ff  hdba: 0x010000fa
    itli: 1  ispac: 0  maxfr: 4858
    tabn: 0 slot: 0(0x0)
    CHANGE #3 TYP:0 CLS:1 AFN:4 DBA:0x010000ff OBJ:22327 SCN:0x0000.003eec75 SEQ:1 OP:11.2 ENC:0 RBL:0   -- OP:11.2 这个应该是插入的操作的了。
    KTB Redo               ----- AFN:4插入的这个是在4号数据文件中-- OBJ:22327--是插入的对象的OBJECT_ID
    op: 0x01  ver: 0x01
    compat bit: 4 (post-11) padding: 1
    op: F  xid:  0x0003.003.00000eaa    uba: 0x00c01ac7.0250.25
    KDO Op code: IRP row dependencies Disabled
      xtype: XA flags: 0x00000000  bdba: 0x010000ff  hdba: 0x010000fa
    itli: 1  ispac: 0  maxfr: 4858
    tabn: 0 slot: 0(0x0) size/delt: 17
    fb: --H-FL-- lb: 0x1  cc: 3
    null: ---
    col  0: [ 2]  c1 22    ---插入语句是:insert into dept values(33,'imutest','hz');  对应是:select dump(33,16) from dual;  --要注意数字在DUMP时不要加单引号
    col  1: [ 7]  69 6d 75 74 65 73 74    --对应select dump('imutest',16) from dual;    [7]--中括号里的是字节数,col  1:对应的是第二列,
    col  2: [ 2]  68 7a    ---对应 select dump('hz',16) from dual;    --中括号里的是字节数  col  2: 对应 的是第三列

    REDO RECORD - Thread:1 RBA: 0x000136.0000000d.01b0 LEN: 0x0060 VLD: 0x01
    SCN: 0x0000.00702f09 SUBSCN:  1 01/06/2014 20:34:13                                                    ---- OP:5.4,提交操作
    CHANGE #1 TYP:0 CLS:21 AFN:3 DBA:0x00c000a0 OBJ:4294967295 SCN:0x0000.00702f08 SEQ:1 OP:5.4 ENC:0 RBL:0
    ktucm redo: slt: 0x0003 sqn: 0x00000eaa srt: 0 sta: 9 flg: 0x2 ktucf redo: uba: 0x00c01ac7.0250.25ext: 12 spc: 3380 fbi: 0

    ############################

    实验二:update 操作的REDO日志解读

    会话3: --SYS用户切换日志:
    SYS@ bys3>alter system switch logfile;
    System altered.
    SYS@ bys3>col  MEMBER for a30
    SYS@ bys3>select a.group#,a.sequence#,a.archived,a.status,b.type,b.member from v$log a,v$logfile b where a.group#=b.group#;
        GROUP#  SEQUENCE# ARC STATUS           TYPE    MEMBER
    ---------- ---------- --- ---------------- ------- ------------------------------
             1        310 YES ACTIVE           ONLINE  /u01/oradata/bys3/redo01.log
             2        311 NO  CURRENT          ONLINE  /u01/oradata/bys3/redo02.log
             3        309 YES INACTIVE         ONLINE  /u01/oradata/bys3/redo03.log
    切换到普通用户做更新语句:
    SYS@ bys3>conn bys/bys
    Connected.
    BYS@ bys3>select * from dept;
        DEPTNO DNAME          LOC
    ---------- -------------- -------------
            10 ACCOUNTING     NEW YORK
            20 RESEARCH       DALLAS
            40 OPERATIONS     BOSTON
            11 chedan         bj
            22 test           sh
            33 imutest        hz
    6 rows selected.
    BYS@ bys3>set time on
    20:39:23 BYS@ bys3>update dept set dname='database' where deptno=11;
    1 row updated.
    20:39:43 BYS@ bys3>commit;
    Commit complete.
    20:39:46 BYS@ bys3>


    会话4:DUMP当前REDO日志:
    SYS@ bys3>alter system dump logfile '/u01/oradata/bys3/redo02.log';
    System altered.
    SYS@ bys3>select value from v$diag_info where name like 'De%' ;
    VALUE
    ----------------------------------------------------------------------------------------------------
    /u01/diag/rdbms/bys3/bys3/trace/bys3_ora_29141.trc
    ##############
    查看此TRACE文件: 方法是:vi /u01/diag/rdbms/bys3/bys3/trace/bys3_ora_29141.trc 然后搜索修改的对象的OBJECT_ID:22327       
           
    UPDATE 一行记录产生一个REDO RECORD,提交产生一个REDO RECORD。非IMU下如果一个UPDATE更新多行,则会产生多条REDO RECORD。关于这个UPDATE语句 产生多少REDO RECORD的话题详见另一篇: 非IMU模式下一条update语句产生REDO RECORD条数的探究
    ###### 一个REDO RECORD: RECORD头+CHANGE VECTOR组成(一个CV就是一个操作)
    REDO RECORD - Thread:1 RBA: 0x000137.00000003.0010 LEN: 0x01ec VLD: 0x05
    SCN: 0x0000.00702fe0 SUBSCN:  1 01/06/2014 20:39:45
    (LWN RBA: 0x000137.00000003.0010 LEN: 0001 NST: 0001 SCN: 0x0000.00702fdf)
    ##以上是日志头,Thread:1 线程号,RAC时会有1,2等
    RBA: 0x000137.00000003.0010 将16进制转换为十进制分别是日志文件号、日志块号、在块上第N字节
    VLD: 0x05日志类型;
    SCN: 0x0000.00702fe0 SUBSCN:  1 01/06/2014 20:39:45    
    --是此REDO条目产生时的SCN号,转为十进制现转为时间戳为:06-JAN-14 08.39.42,  更新语句完成是在20:39:43 BYS@bys3>commit;
    (LWN RBA: 0x000137.00000003.0010 LEN: 0001 NST: 0001 SCN: 0x0000.00702fdf)
    括号中SCN: SCN: 0x0000.00702fdf  比上一句:SCN: 0x0000.00702fe0 SUBSCN:  1 01/06/2014 20:39:45    少了1个SCN。
    ######
    CHANGE #1 TYP:0 CLS:17 AFN:3 DBA:0x00c00080 OBJ:4294967295 SCN:0x0000.00702f9a SEQ:1 OP:5.2 ENC:0 RBL:0
    ktudh redo: slt: 0x000f sqn: 0x00000e9c flg: 0x0012 siz: 164 fbi: 0
                uba: 0x00c01cbf.0250.0f    pxid:  0x0000.000.00000000
    ### ##################### 事务信息
    TYP:0 普通块 ,CLS:17 class大于16是UNDO块-递增。AFN:3 绝对文件号dba_data_files.file_id--这里是UNDO文件的文件号
    DBA:0x00c00080 数据块在内存中地址
    OBJ:4294967295 --十进制,转为16进制是FFFFFFFF
    SCN:0x0000.00702f9a  转换为16进制可与操作时对比
    OP:5.2 -> operation code 向UNDO段头的事务表写事务信息-事务开始
    uba: 0x00c01cbf.0250.0f  UNDO块地址

    ####################
    CHANGE #2 TYP:0 CLS:18 AFN:3 DBA:0x00c01cbf OBJ:4294967295 SCN:0x0000.00702f99 SEQ:2 OP:5.1 ENC:0 RBL:0
    ## OP:5.1 --把数据修改前值放到UNDO   --AFN:3 --在UNDO文件里操作,UNDO文件号是3。。 CLS:18 --比 CHANGE #1中大1,顺序增长哈哈
    ktudb redo: siz: 164 spc: 6494 flg: 0x0012 seq: 0x0250 rec: 0x0f
                xid:  0x0001.00f.00000e9c
    ktubl redo: slt: 15 rci: 0 opc: 11.1 [objn: 22327 objd: 22327 tsn: 4]    ------- tsn: 4插入的这个是在表空间号-USERS的表空间号,-- OBJ:22327--是插入的对象的OBJECT_ID
    Undo type:  Regular undo        Begin trans    Last buffer split:  No
    Temp Object:  No
    Tablespace Undo:  No
                 0x00000000  prev ctl uba: 0x00c01cbf.0250.0d
    prev ctl max cmt scn:  0x0000.00702afa  prev tx cmt scn:  0x0000.00702b2e
    txn start scn:  0xffff.ffffffff  logon user: 32  prev brb: 12590267  prev bcl: 0 BuExt idx: 0 flg2: 0
    KDO undo record:
    KTB Redo
    op: 0x04  ver: 0x01
    compat bit: 4 (post-11) padding: 1
    op: L  itl: xid:  0x0005.008.00000e9d uba: 0x00c01840.02e4.13
                          flg: C---    lkc:  0     scn: 0x0000.00702b1f
    KDO Op code: URP row dependencies Disabled
      xtype: XA flags: 0x00000000  bdba: 0x010000fd  hdba: 0x010000fa
    itli: 1  ispac: 0  maxfr: 4858
    tabn: 0 slot: 5(0x5) flag: 0x2c lock: 0 ckix: 0
    ncol: 3 nnew: 1 size: -2   ##列字符长度减少2: chedan减去database就是-2---根据多次update并DUMP的日志来看,这里的 size的值应该是:当前 CHANGE中的值减去另一个
    col  1: [ 6]  63 68 65 64 61 6e   --修改语句是:update dept set dname='database' where deptno=11; deptno=11时的为chedan-DUMP为16进制,与col  1: [ 6]  63 68 65 64 61 6e对应,[ 6]
    chedan对应, col  1是第二列--修改的dname列就是第二列。
    SYS@ bys3> select dump('chedan',16) from dual;
    DUMP('CHEDAN',16)
    -------------------------------
    Typ=96 Len=6: 63,68,65,64,61,6e
    ##############
    CHANGE #3 TYP:2 CLS:1 AFN:4DBA:0x010000fd OBJ:22327 SCN:0x0000.00702d7aSEQ:1 OP:11.5 ENC:0 RBL:0
    ## OP:11.19 或者OP:11.5都是--UPDATE语句,开始修改数据,  AFN:4 --这次是在USERS表空间修改数据-文件号就是4
    KTB Redo
    op: 0x11  ver: 0x01
    compat bit: 4 (post-11) padding: 1
    op: F  xid:  0x0001.00f.00000e9c    uba: 0x00c01cbf.0250.0f
    Block cleanout record, scn:  0x0000.00702fe0 ver: 0x01 opt: 0x02, entries follow...
      itli: 1  flg: 2  scn: 0x0000.00702b1f
      itli: 2  flg: 2  scn: 0x0000.00702d7a
    KDO Op code: URP row dependencies Disabled
    ###此语句也说明是UPDATE语句,URP row dependencies Disabled --URP=UPDATE ROW PIECE。有时会是:KDO Op code:21 row dependencies Disabled
      xtype: XA flags: 0x00000000  bdba: 0x010000fd  hdba: 0x010000fa
    itli: 1  ispac: 0  maxfr: 4858
    tabn: 0 slot: 5(0x5) flag: 0x2c lock: 1 ckix: 0
    ncol: 3 nnew: 1 size: 2   ##size: 2,列字符长度增加2:database减去 chedan---根据多次update并DUMP的日志来看,这里的 size的值应该是:当前 CHANGE中的值减去另一个
    col  1: [ 8]  64 61 74 61 62 61 73 65   ---update dept set dname='database' where deptno=11;,对应 select dump('database',16) from dual;    col  1: [ 8]  ---第二列,8位,
    ####################################################
    REDO RECORD - Thread:1 RBA: 0x000137.00000004.0010 LEN: 0x008c VLD: 0x05
    SCN: 0x0000.00702fe2 SUBSCN:  1 01/06/2014 20:39:46
    (LWN RBA: 0x000137.00000004.0010 LEN: 0001 NST: 0001 SCN: 0x0000.00702fe1)
    CHANGE #1 TYP:0 CLS:17 AFN:3 DBA:0x00c00080 OBJ:4294967295 SCN:0x0000.00702fe0 SEQ:1 OP:5.4 ENC:0 RBL:0
    ktucm redo: slt: 0x000f sqn: 0x00000e9c srt: 0 sta: 9 flg: 0x2 ktucf redo: uba: 0x00c01cbf.0250.0f ext: 4 spc: 6328 fbi: 0
    ###########
    OP:5.4 表明是提交操作。
    CHANGE #1 TYP:0 CLS:17 AFN:3 DBA:0x00c00080 OBJ:4294967295 SCN:0x0000.00702fe0 SEQ:1 OP:5.4 ENC:0 RBL:0
    AFN:3 对应的是UNDO文件,
    slt: 0x000f  修改了UNDO文件的这个事务槽


    SCN: 0x0000.00702fe2 SUBSCN:  1 01/06/2014 20:39:46  提交操作的时间 :
    20:39:43 BYS@ bys3>commit;
    Commit complete.
    20:39:46 BYS@ bys3>
    ########################################

    实验三:delete 操作的REDO日志解读

    会话5: --SYS用户切换日志:
    alter system switch logfile;
    SYS@ bys3>col member for a30
    SYS@ bys3>select a.group#,a.sequence#,a.archived,a.status,b.type,b.member from v$log a,v$logfile b where a.group#=b.group#;
        GROUP#  SEQUENCE# ARC STATUS           TYPE    MEMBER
    ---------- ---------- --- ---------------- ------- ------------------------------
             1        310 YES INACTIVE         ONLINE  /u01/oradata/bys3/redo01.log
             2        311 YES ACTIVE           ONLINE  /u01/oradata/bys3/redo02.log
             3        312 NO  CURRENT          ONLINE  /u01/oradata/bys3/redo03.log
    切换到普通用户做删除语句:
    conn bys/bys
    BYS@ bys3>select * from dept;
        DEPTNO DNAME          LOC
    ---------- -------------- -------------
            10 ACCOUNTING     NEW YORK
            20 RESEARCH       DALLAS
            40 OPERATIONS     BOSTON
            11 database       bj
            22 test           sh
            33 imutest        hz
    6 rows selected.
    BYS@ bys3>set time on
    20:43:18 BYS@ bys3>delete dept where deptno=33;
    1 row deleted.
    20:43:25 BYS@ bys3>commit;
    Commit complete.
    会话6,DUMP当前REDO日志:
    SYS@ bys3>alter system dump logfile '/u01/oradata/bys3/redo03.log';
    System altered.
    SYS@ bys3>select value from v$diag_info where name like 'De%' ;
    VALUE
    ----------------------------------------------------------------------------------------------------
    /u01/diag/rdbms/bys3/bys3/trace/bys3_ora_29214.trc
    ##############
    查看此TRACE文件: 方法是:vi /u01/diag/rdbms/bys3/bys3/trace/bys3_ora_29214.trc 然后搜索修改的对象的OBJECT_ID:22327

    REDO RECORD - Thread:1 RBA: 0x000138.0000002b.0010 LEN: 0x01c8 VLD: 0x05
    SCN: 0x0000.0070306c SUBSCN:  1 01/06/2014 20:43:26
    (LWN RBA: 0x000138.0000002b.0010 LEN: 0002 NST: 0001 SCN: 0x0000.0070306b)
    CHANGE #1 TYP:0 CLS:29 AFN:3 DBA:0x00c000e0 OBJ:4294967295 SCN:0x0000.0070303f SEQ:1 OP:5.2 ENC:0 RBL:0
    ktudh redo: slt: 0x0008 sqn: 0x00000e9b flg: 0x0012 siz: 168 fbi: 0
                uba: 0x00c0193e.02b8.03    pxid:  0x0000.000.00000000
    CHANGE #2 TYP:0 CLS:30 AFN:3 DBA:0x00c0193e OBJ:4294967295 SCN:0x0000.0070303e SEQ:1 OP:5.1 ENC:0 RBL:0
    ktudb redo: siz: 168 spc: 7794 flg: 0x0012 seq: 0x02b8 rec: 0x03
                xid:  0x0007.008.00000e9b
    ktubl redo: slt: 8 rci: 0 opc: 11.1 [objn: 22327 objd: 22327 tsn: 4]
    Undo type:  Regular undo        Begin trans    Last buffer split:  No
    Temp Object:  No
    Tablespace Undo:  No
                 0x00000000  prev ctl uba: 0x00c0193e.02b8.02
    prev ctl max cmt scn:  0x0000.00702b2d  prev tx cmt scn:  0x0000.00702b3e
    txn start scn:  0xffff.ffffffff  logon user: 32  prev brb: 12589367  prev bcl: 0 BuExt idx: 0 flg2: 0
    KDO undo record:
    KTB Redo
    op: 0x03  ver: 0x01
    compat bit: 4 (post-11) padding: 1
    op: Z
    KDO Op code: IRP row dependencies Disabled
      xtype: XA flags: 0x00000000  bdba: 0x010000ff  hdba: 0x010000fa
    itli: 2  ispac: 0  maxfr: 4858
    tabn: 0 slot: 0(0x0) size/delt: 17
    fb: --H-FL-- lb: 0x0  cc: 3
    null: ---
    col  0: [ 2]  c1 22    ---记录删除前的原值,delete dept where deptno=33;   删除的是这一行值: 33 imutest        hz
    col  1: [ 7]  69 6d 75 74 65 73 74

    col  2: [ 2]  68 7a
    ###################
    BYS@ bys3>select dump(33,16),dump('imutest',16),dump('hz',16) from dual;
    DUMP(33,16)        DUMP('IMUTEST',16)                 DUMP('HZ',16)
    ------------------ ---------------------------------- -------------------
    Typ=2 Len=2: c1,22 Typ=96 Len=7: 69,6d,75,74,65,73,74 Typ=96 Len=2: 68,7a
    #####################

    CHANGE #3 TYP:2 CLS:1 AFN:4 DBA:0x010000ff OBJ:22327 SCN:0x0000.00702f09 SEQ:1 OP:11.3 ENC:0 RBL:0
    KTB Redo
    op: 0x11  ver: 0x01
    compat bit: 4 (post-11) padding: 1
    op: F  xid:  0x0007.008.00000e9b    uba: 0x00c0193e.02b8.03
    Block cleanout record, scn:  0x0000.0070306c ver: 0x01 opt: 0x02, entries follow...
      itli: 1  flg: 2  scn: 0x0000.00702f09
    KDO Op code: DRP row dependencies Disabled
      xtype: XA flags: 0x00000000  bdba: 0x010000ff  hdba: 0x010000fa
    itli: 2  ispac: 0  maxfr: 4858
    tabn: 0 slot: 0(0x0)

    REDO RECORD - Thread:1 RBA: 0x000138.0000002b.01d8 LEN: 0x0060 VLD: 0x01
    SCN: 0x0000.0070306d SUBSCN:  1 01/06/2014 20:43:26
    CHANGE #1 TYP:0 CLS:29 AFN:3 DBA:0x00c000e0 OBJ:4294967295 SCN:0x0000.0070306c SEQ:1 OP:5.4 ENC:0 RBL:0
    ktucm redo: slt: 0x0008 sqn: 0x00000e9b srt: 0 sta: 9 flg: 0x2 ktucf redo: uba: 0x00c0193e.02b8.03 ext: 3 spc: 7624 fbi: 0

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  • 原文地址:https://www.cnblogs.com/fuhaots2009/p/3508732.html
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