Oracle内核的进步 ---- 新、老Redo机制对比
体系结构
非IMU下的redo产生过程
--分析redo log（update）
SQL> set sqlprompt "_USER@ _CONNECT_IDENTIFIER >" SYS@ orcl >@?/rdbms/admin/show_para Enter value for p: in_memory_undo old 12: AND upper(i.ksppinm) LIKE upper('%&p%') new 12: AND upper(i.ksppinm) LIKE upper('%in_memory_undo%') P_NAME P_DESCRIPTION P_VALUE ISDEFAULT ISMODIFIED ISADJ ---------------------------------------- -------------------------------------------------- ------------------------------ --------- ---------- ----- _in_memory_undo Make in memory undo for top level transactions TRUE TRUE FALSE FALSE SYS@ orcl >set linesize 1000 create table redo_test(id int,name varchar2(20)); insert into redo_test(id,name)values(1,'AAAAAAAAAAA'); insert into redo_test(id,name)values(2,'BBBBBBBBBBBBB'); COMMIT; SYS@ orcl >SELECT * FROM TEST.REDO_TEST; ID NAME ---------- -------------------- 1 AAAAAAAAAAA 2 BBBBBBBBBBBBB SYS@ orcl >alter system switch logfile; System altered. SYS@ orcl >select * from v$Log; GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME ---------- ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- ------------ --------- 1 1 7 52428800 512 2 NO INACTIVE 9800422 12-JUN-19 9800537 12-JUN-19 2 1 8 52428800 512 1 NO ACTIVE 9800537 12-JUN-19 9803089 12-JUN-19 3 1 9 52428800 512 1 NO CURRENT 9803089 12-JUN-19 2.8147E+14
[root@DSI ~]# strings /u01/app/oracle/oradata/orcl/redo03.log |grep redo_test [root@DSI ~]# strings /u01/app/oracle/oradata/orcl/redo02.log |grep redo_test create table redo_test(id int,name varchar2(20)) SYS@ orcl >alter system set "_in_memory_undo"=false; System altered. SYS@ orcl >select * from test.redo_test; ID NAME ---------- -------------------- 1 AAAAAAAAAAA 2 BBBBBBBBBBBBB SYS@ orcl >update test.redo_test set name='cccccc' where rownum<=2; 2 rows updated. SYS@ orcl >commit; Commit complete. SYS@ orcl >select object_id from user_objects where object_name='REDO_TEST'; no rows selected SYS@ orcl >conn test/test Connected. TEST@ orcl >select object_id from user_objects where object_name='REDO_TEST'; OBJECT_ID ---------- 87535 TEST@ orcl >conn / as sysdba Connected. SYS@ orcl > alter system dump logfile '/u01/app/oracle/oradata/orcl/redo03.log'; System altered. SYS@ orcl >oradebug setmypid Statement processed. SYS@ orcl >oradebug tracefile_name /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_3137.trc
[root@DSI ~]# vim /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_ora_3137.trc
##根据上面查到的object_id=87535 去日志中搜索
三条日志：
第一条日志：
日志头
OP=5.2 ==>事务开始了
OP=5.1 ==>把数据前的值放到UNDO块
OP=11.5 ==>update修改数据
第二条日志：
日志头
OP=5.1 ==>把数据前的值放到UNDO块
OP=11.5 ==>update修改数据
第三条日志：
日志头
OP=5.4 ==>提交（事务结束）
三条日志：REDO RECORD 第一个REDO RECORD: REDO RECORD头+CHANGE VECTOR组成（一个CV就是一个操作），由三个CV组成 REDO RECORD - Thread:1 RBA: 0x000009.00000289.0010 LEN: 0x0224 VLD: 0x05 SCN: 0x0000.00959714 SUBSCN: 1 06/12/2019 16:20:54 (LWN RBA: 0x000009.00000289.0010 LEN: 0002 NST: 0001 SCN: 0x0000.00959713) -------------------------------------------------------》REDO RECORD头 RBA: 0x000009.00000289.0010==（由三部分组成序列号，块号，偏移量或着叫第几个字节）--redo log循环写，0x000009日志序列号累加（对应v$Log中SEQUENCE#的值） LEN: 0x0224：一条日志的长度 VLD: 0x05 ：日志类型 CHANGE #1 TYP:0 CLS:25 AFN:3 DBA:0x00c000c0 OBJ:4294967295 SCN:0x0000.00959703 SEQ:1 OP:5.2 ENC:0 RBL:0 ktudh redo: slt: 0x0003 sqn: 0x0000202f flg: 0x0012 siz: 168 fbi: 0 uba: 0x00c028ae.01ae.0a pxid: 0x0000.000.00000000 ------------------------------------------------------------------------->UNDO段头事务表 OP:5.2==》OPRATION CODE 向UNDO段的段头的事务表写事务信息 TYP:0（普通块） CLS:25 （CLASS） AFN:3 (绝对文件号) DBA:0x00c000c0 数据块的地址 OBJ:4294967295 FFFFFFFF SCN:0x0000.00959703 产生事务的时间 CHANGE #2 TYP:0 CLS:26 AFN:3 DBA:0x00c028ae OBJ:4294967295 SCN:0x0000.00959702 SEQ:3 OP:5.1 ENC:0 RBL:0 ktudb redo: siz: 168 spc: 6416 flg: 0x0012 seq: 0x01ae rec: 0x0a xid: 0x0005.003.0000202f ktubl redo: slt: 3 rci: 0 opc: 11.1 [objn: 87535 objd: 87535 tsn: 5] Undo type: Regular undo Begin trans Last buffer split: No Temp Object: No Tablespace Undo: No 0x00000000 prev ctl uba: 0x00c028ae.01ae.07 prev ctl max cmt scn: 0x0000.00959318 prev tx cmt scn: 0x0000.00959328 txn start scn: 0xffff.ffffffff logon user: 0 prev brb: 12593324 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: URP row dependencies Disabled xtype: XA flags: 0x00000000 bdba: 0x0140313f hdba: 0x0140313a itli: 2 ispac: 0 maxfr: 4858 tabn: 0 slot: 0(0x0) flag: 0x2c lock: 0 ckix: 0 ncol: 2 nnew: 1 size: 5 col 1: [11] 41 41 41 41 41 41 41 41 41 41 41 ————————————————————————————————》undo数据块 CHANGE #3 TYP:2 CLS:1 AFN:5 DBA:0x0140313f OBJ:87535 SCN:0x0000.0095953a SEQ:1 OP:11.5 ENC:0 RBL:0 KTB Redo op: 0x11 ver: 0x01 compat bit: 4 (post-11) padding: 1 op: F xid: 0x0005.003.0000202f uba: 0x00c028ae.01ae.0a Block cleanout record, scn: 0x0000.00959714 ver: 0x01 opt: 0x02, entries follow... itli: 1 flg: 2 scn: 0x0000.0095953a KDO Op code: URP row dependencies Disabled xtype: XA flags: 0x00000000 bdba: 0x0140313f hdba: 0x0140313a itli: 2 ispac: 0 maxfr: 4858 tabn: 0 slot: 0(0x0) flag: 0x2c lock: 2 ckix: 0 ncol: 2 nnew: 1 size: -5 col 1: [ 6] 63 63 63 63 63 63 -----------------------------------------------------------》数据修改后的值 OP:11.5===》UPDATE操作
第二条REDO REDO RECORD - Thread:1 RBA: 0x000009.0000028a.0044 LEN: 0x0124 VLD: 0x01 SCN: 0x0000.00959714 SUBSCN: 2 06/12/2019 16:20:54 CHANGE #1 TYP:0 CLS:26 AFN:3 DBA:0x00c028ae OBJ:4294967295 SCN:0x0000.00959714 SEQ:1 OP:5.1 ENC:0 RBL:0 ktudb redo: siz: 128 spc: 6246 flg: 0x0022 seq: 0x01ae rec: 0x0b xid: 0x0005.003.0000202f ktubu redo: slt: 3 rci: 10 opc: 11.1 objn: 87535 objd: 87535 tsn: 5 Undo type: Regular undo Undo type: Last buffer split: No Tablespace Undo: No 0x00000000 KDO undo record: KTB Redo op: 0x02 ver: 0x01 compat bit: 4 (post-11) padding: 1 op: C uba: 0x00c028ae.01ae.0a KDO Op code: URP row dependencies Disabled xtype: XA flags: 0x00000000 bdba: 0x0140313f hdba: 0x0140313a itli: 2 ispac: 0 maxfr: 4858 tabn: 0 slot: 1(0x1) flag: 0x2c lock: 0 ckix: 0 ncol: 2 nnew: 1 size: 7 col 1: [13] 42 42 42 42 42 42 42 42 42 42 42 42 42 CHANGE #2 TYP:0 CLS:1 AFN:5 DBA:0x0140313f OBJ:87535 SCN:0x0000.00959714 SEQ:1 OP:11.5 ENC:0 RBL:0 KTB Redo op: 0x02 ver: 0x01 compat bit: 4 (post-11) padding: 1 op: C uba: 0x00c028ae.01ae.0b KDO Op code: URP row dependencies Disabled xtype: XA flags: 0x00000000 bdba: 0x0140313f hdba: 0x0140313a itli: 2 ispac: 0 maxfr: 4858 tabn: 0 slot: 1(0x1) flag: 0x2c lock: 2 ckix: 0 ncol: 2 nnew: 1 size: -7 col 1: [ 6] 63 63 63 63 63 63
第三条RECORD 提交OP:5.4作为单独的一条RECORD REDO RECORD - Thread:1 RBA: 0x000009.0000028b.0010 LEN: 0x00d0 VLD: 0x05 SCN: 0x0000.00959716 SUBSCN: 1 06/12/2019 16:20:56 (LWN RBA: 0x000009.0000028b.0010 LEN: 0001 NST: 0001 SCN: 0x0000.00959715) CHANGE #1 TYP:0 CLS:25 AFN:3 DBA:0x00c000c0 OBJ:4294967295 SCN:0x0000.00959714 SEQ:1 OP:5.4 ENC:0 RBL:0 ktucm redo: slt: 0x0003 sqn: 0x0000202f srt: 0 sta: 9 flg: 0x2 ktucf redo: uba: 0x00c028ae.01ae.0b ext: 2 spc: 6116 fbi: 0 CHANGE #2 MEDIA RECOVERY MARKER SCN:0x0000.00000000 SEQ:0 OP:24.4 ENC:0
非IMU下，在一个事务下面分别做两条UPDATE
SYS@ orcl >update test.redo_test set name='aaa' where id=1; 1 row updated. SYS@ orcl >update test.redo_test set name='bbb' where id=2; 1 row updated. SYS@ orcl >commit; Commit complete. REDO RECORD - Thread:1 RBA: 0x000009.000002ed.0010 LEN: 0x0144 VLD: 0x05 SCN: 0x0000.009598d3 SUBSCN: 1 06/12/2019 16:39:56 (LWN RBA: 0x000009.000002ed.0010 LEN: 0001 NST: 0001 SCN: 0x0000.009598d2) CHANGE #1 TYP:0 CLS:34 AFN:3 DBA:0x00c0021b OBJ:4294967295 SCN:0x0000.009598ca SEQ:1 OP:5.1 ENC:0 RBL:0 ktudb redo: siz: 120 spc: 6104 flg: 0x0022 seq: 0x01bf rec: 0x0c xid: 0x0009.01a.00005b60 ktubu redo: slt: 26 rci: 11 opc: 11.1 objn: 87535 objd: 87535 tsn: 5 Undo type: Regular undo Undo type: Last buffer split: No Tablespace Undo: No 0x00000000 KDO undo record: KTB Redo op: 0x02 ver: 0x01 compat bit: 4 (post-11) padding: 1 op: C uba: 0x00c0021b.01bf.0b KDO Op code: URP row dependencies Disabled xtype: XA flags: 0x00000000 bdba: 0x0140313f hdba: 0x0140313a itli: 1 ispac: 0 maxfr: 4858 tabn: 0 slot: 1(0x1) flag: 0x2c lock: 0 ckix: 0 ncol: 2 nnew: 1 size: 3 col 1: [ 6] 63 63 63 63 63 63 CHANGE #2 TYP:0 CLS:1 AFN:5 DBA:0x0140313f OBJ:87535 SCN:0x0000.009598ca SEQ:1 OP:11.5 ENC:0 RBL:0 KTB Redo op: 0x02 ver: 0x01 compat bit: 4 (post-11) padding: 1 op: C uba: 0x00c0021b.01bf.0c KDO Op code: URP row dependencies Disabled xtype: XA flags: 0x00000000 bdba: 0x0140313f hdba: 0x0140313a itli: 1 ispac: 0 maxfr: 4858 tabn: 0 slot: 1(0x1) flag: 0x2c lock: 1 ckix: 0 ncol: 2 nnew: 1 size: -3 col 1: [ 3] 62 62 62 REDO RECORD - Thread:1 RBA: 0x000009.000002ee.0010 LEN: 0x00d0 VLD: 0x05 SCN: 0x0000.009598d6 SUBSCN: 1 06/12/2019 16:39:59 (LWN RBA: 0x000009.000002ee.0010 LEN: 0001 NST: 0001 SCN: 0x0000.009598d5) CHANGE #1 TYP:0 CLS:33 AFN:3 DBA:0x00c00100 OBJ:4294967295 SCN:0x0000.009598ca SEQ:1 OP:5.4 ENC:0 RBL:0 ktucm redo: slt: 0x001a sqn: 0x00005b60 srt: 0 sta: 9 flg: 0x2 ktucf redo: uba: 0x00c0021b.01bf.0c ext: 2 spc: 5982 fbi: 0 CHANGE #2 MEDIA RECOVERY MARKER SCN:0x0000.00000000 SEQ:0 OP:24.4 ENC:0 redo log中以行修改记录
在IMU下
SYS@ orcl >alter system set "_in_memory_undo"=true; SYS@ orcl >show parameter in_memory_undo NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ _in_memory_undo boolean TRUE SYS@ orcl >shutdown immediate; SYS@ orcl >startup update test.redo_test set name='ccccc' where id=1; update test.redo_test set name='ddddd' where id=2;
REDO RECORD - Thread:1 RBA: 0x00000b.00000002.0010 LEN: 0x0234 VLD: 0x05 SCN: 0x0000.00959bad SUBSCN: 1 06/12/2019 16:54:11 (LWN RBA: 0x00000b.00000002.0010 LEN: 0002 NST: 0001 SCN: 0x0000.00959baa) CHANGE #1 TYP:0 CLS:29 AFN:3 DBA:0x00c000e0 OBJ:4294967295 SCN:0x0000.00959aae SEQ:1 OP:5.2 ENC:0 RBL:0 ktudh redo: slt: 0x001d sqn: 0x0000455c flg: 0x0012 siz: 184 fbi: 0 uba: 0x00c0388d.0246.0d pxid: 0x0000.000.00000000 CHANGE #2 TYP:0 CLS:30 AFN:3 DBA:0x00c0388d OBJ:4294967295 SCN:0x0000.00959a81 SEQ:1 OP:5.1 ENC:0 RBL:0 ktudb redo: siz: 184 spc: 5038 flg: 0x0012 seq: 0x0246 rec: 0x0d xid: 0x0007.01d.0000455c ktubl redo: slt: 29 rci: 0 opc: 11.1 [objn: 87535 objd: 87535 tsn: 5] Undo type: Regular undo Begin trans Last buffer split: No Temp Object: No Tablespace Undo: No 0x00000000 prev ctl uba: 0x00c0388d.0246.0c prev ctl max cmt scn: 0x0000.00959429 prev tx cmt scn: 0x0000.0095951a txn start scn: 0xffff.ffffffff logon user: 0 prev brb: 12597387 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: 0x0005.003.0000202f uba: 0x00c028ae.01ae.0b flg: C--- lkc: 0 scn: 0x0000.00959716 KDO Op code: URP row dependencies Disabled xtype: XA flags: 0x00000000 bdba: 0x0140313f hdba: 0x0140313a itli: 2 ispac: 0 maxfr: 4858 tabn: 0 slot: 0(0x0) flag: 0x2c lock: 0 ckix: 0 ncol: 2 nnew: 1 size: -2 col 1: [ 3] 61 61 61 CHANGE #3 TYP:2 CLS:1 AFN:5 DBA:0x0140313f OBJ:87535 SCN:0x0000.009598d6 SEQ:1 OP:11.5 ENC:0 RBL:0 KTB Redo op: 0x11 ver: 0x01 compat bit: 4 (post-11) padding: 1 op: F xid: 0x0007.01d.0000455c uba: 0x00c0388d.0246.0d Block cleanout record, scn: 0x0000.00959bad ver: 0x01 opt: 0x02, entries follow... itli: 1 flg: 2 scn: 0x0000.009598d6 KDO Op code: URP row dependencies Disabled xtype: XA flags: 0x00000000 bdba: 0x0140313f hdba: 0x0140313a itli: 2 ispac: 0 maxfr: 4858 tabn: 0 slot: 0(0x0) flag: 0x2c lock: 2 ckix: 0 ncol: 2 nnew: 1 size: 2 col 1: [ 5] 63 63 63 63 63
---这里分析redo log，还是在非imu下的redo 格式，没有达到想要的目的
在IMU模式下的update的redo，
一条记日志==》6个CHANGE VECTOR
CHANGE #1 ==>OP:11.5 -->UPDATE
CHANGE #2 ==>OP:5.2 -->开始一个事务
CHANGE #3 ==>OP:11.5 —>UPDATE
CHANGE #4 ==>OP:5.4 --->COMMIT
CHANGE #5 ==>OP:5.1 --->UNDO
CHANGE #6 ==>OP:5.1 --->UNDO
非IMU
产生一条REDO RECORD的步骤
1、获取redo copy Latch
2、获取redo allocate Latch
3、申请到LOG BUFFER空间
4、释放redo allocate Latch
5、生产日志（从buffer cache copy 修改前的值。从PGA copy 修改后的值），产生日志头
6、释放redo copy Latch
SYS@ orcl >select latch#,name from v$latch where name like '%redo%'; LATCH# NAME ---------- ---------------------------------------------------------------- 168 redo on-disk SCN 169 ping redo on-disk SCN 207 redo writing 208 redo copy 209 redo allocation 210 real redo SCN 212 readredo stats and histogram 238 readable standby metadata redo cache 544 KFR redo allocation latch 9 rows selected.
IMU--->把多条日志条目合并成一条，减少LATCH
多出一个IMU LATCH
附录：op操作代码
格式：layer: opcode LAYER的含义： 4 — Block Cleanout 5 — Transaction Management 10 — 索引操作 11 — 行操作 13 — 段[url=]管理[/url] 14 — Extent 管理 17 — 表空间管理 18 — Block Image (Hot Backups) 19 — Direct Loader 20 — Compatibility segment 22 — 本地管理表空间 23 — Block Writes 24 — DDL语句 Layer 1 : Transaction Control - KCOCOTCT Opcode 1 : KTZFMT Opcode 2 : KTZRDH Opcode 3 : KTZARC Opcode 4 : KTZREP Layer 2 : Transaction Read - KCOCOTRD Layer 3 : Transaction Update - KCOCOTUP Layer 4 : Transaction Block - KCOCOTBK [ktbcts.h] Opcode 1 : Block Cleanout Opcode 2 : Physical Cleanout Opcode 3 : Single Array Change Opcode 4 : Multiple Changes to an Array Opcode 5 : Format Block Layer 5 : Transaction Undo - KCOCOTUN [ktucts.h] Opcode 1 : Undo block or undo segment header - KTURDB Opcode 2 : Update rollback segment header - KTURDH Opcode 3 : Rollout a transaction begin Opcode 4 : Commit transaction (transaction table update) - no undo record Opcode 5 : Create rollback segment (format) - no undo record Opcode 6 : Rollback record index in an undo block - KTUIRB Opcode 7 : Begin transaction (transaction table update) Opcode 8 : Mark transaction as dead Opcode 9 : Undo routine to rollback the extend of a rollback segment Opcode 10 :Redo to perform the rollback of extend of rollback segment to the segment header. Opcode 11 :Rollback DBA in transaction table entry - KTUBRB Opcode 12 :Change transaction state (in transaction table entry) Opcode 13 :Convert rollback segment format (V6 -> V7) Opcode 14 :Change extent allocation parameters in a rollback segment Opcode 15 : Opcode 16 : Opcode 17 : Opcode 18 : Opcode 19 : Transaction start audit log record Opcode 20 : Transaction continue audit log record Opcode 24 : Kernel Transaction Undo Relog CHanGe - KTURLGU Layer 6 : Control File - KCOCODCF [tbs.h] Layer 10 : INDEX - KCOCODIX [kdi.h] Opcode 1 : load index block (Loader with direct mode) Opcode 2 : Insert leaf row Opcode 3 : Purge leaf row Opcode 4 : Mark leaf row deleted Opcode 5 : Restore leaf row (clear leaf delete flags) Opcode 6 : Lock index block Opcode 7 : Unlock index block Opcode 8 : Initialize new leaf block Opcode 9 : Apply Itl Redo Opcode 10 :Set leaf block next link Opcode 11 :Set leaf block previous link Opcode 12 :Init root block after split Opcode 13 :Make leaf block empty Opcode 14 :Restore block before image Opcode 15 :Branch block row insert Opcode 16 :Branch block row purge Opcode 17 :Initialize new branch block Opcode 18 :Update keydata in row Opcode 19 :Clear row’s split flag Opcode 20 :Set row’s split flag Opcode 21 :General undo above the cache (undo) Opcode 22 :Undo operation on leaf key above the cache (undo) Opcode 23 :Restore block to b-tree Opcode 24 :Shrink ITL (transaction entries) Opcode 25 :Format root block redo Opcode 26 :Undo of format root block (undo) Opcode 27 :Redo for undo of format root block Opcode 28 :Undo for migrating block Opcode 29 :Redo for migrating block Opcode 30 :IOT leaf block nonkey update Opcode 31 :Cirect load root redo Opcode 32 :Combine operation for insert and restore rows Layer 11 : Row Access - KCOCODRW [kdocts.h] Opcode 1 : Interpret Undo Record (Undo) Opcode 2 : Insert Row Piece Opcode 3 : Drop Row Piece Opcode 4 : Lock Row Piece Opcode 5 : Update Row Piece Opcode 6 : Overwrite Row Piece Opcode 7 : Manipulate First Column (add or delete the 1rst column) Opcode 8 : Change Forwarding address Opcode 9 : Change the Cluster Key Index Opcode 10 :Set Key Links (change the forward & backward key links on a cluster key) Opcode 11 :Quick Multi-Insert (ex: insert as select …) Opcode 12 :Quick Multi-Delete Opcode 13 :Toggle Block Header flags Layer 12 : Cluster - KCOCODCL [?] Layer 13 : Transaction Segment - KCOCOTSG [ktscts.h] Opcode 1 : Data segment format Opcode 2 : Merge Opcode 3 : Set link in block Opcode 4 : Not used Opcode 5 : New block (affects segment header) Opcode 6 : Format block (affects data block) Opcode 7 : Record link Opcode 8 : Undo free list (undo) Opcode 9 : Redo free list head (called as part of undo) Opcode 9 : Format free list block (freelist group) Opcode 11 :Format new blocks in free list Opcode 12 :free list clear Opcode 13 :free list restore (back) (undo of opcode 12) Layer 14 : Transaction Extent - KCOCOTEX [kte.h] Opcode 1 : Add extent to segment Opcode 2 : Unlock Segment Header Opcode 3 : Extent DEaLlocation (DEL) Opcode 4 : Undo to Add extent operation (see opcode 1) Opcode 5 : Extent Incarnation number increment Opcode 6 : Lock segment Header Opcode 7 : Undo to rollback extent deallocation (see opcode 3) Opcode 8 : Apply Position Update (truncate) Opcode 9 : Link blocks to Freelist Opcode 10 :Unlink blocks from Freelist Opcode 11 :Undo to Apply Position Update (see opcode 8) Opcode 12 :Convert segment header to 6.2.x type Layer 15 : Table Space - KCOCOTTS [ktt.h] Opcode 1 : Format deferred rollback segment header Opcode 2 : Add deferred rollback record Opcode 3 : Move to next block Opcode 4 : Point to next deferred rollback record Layer 16 : Row Cache - KCOCOQRC Layer 17 : Recovery (REDO) - KCOCORCV [kcv.h] Opcode 1 : End Hot Backup : This operation clears the hot backup in-progress flags in the indicated list of files Opcode 2 : Enable Thread : This operation creates a redo record signalling that a thread has been enabled Opcode 3 : Crash Recovery Marker Opcode 4 : Resizeable datafiles Opcode 5 : Tablespace ONline Opcode 6 : Tablespace OFFline Opcode 7 : Tablespace ReaD Write Opcode 8 : Tablespace ReaD Only Opcode 9 : ADDing datafiles to database Opcode 10 : Tablespace DRoP Opcode 11 : Tablespace PitR Layer 18 : Hot Backup Log Blocks - KCOCOHLB [kcb.h] Opcode 1 : Log block image Opcode 2 : Recovery testing Layer 19 : Direct Loader Log Blocks - KCOCODLB [kcbl.h] Opcode 1 : Direct block logging Opcode 2 : Invalidate range Opcode 3 : Direct block relogging Opcode 4 : Invalidate range relogging Layer 20 : Compatibility Segment operations - KCOCOKCK [kck.h] Opcode 1 : Format compatibility segment - KCKFCS Opcode 2 : Update compatibility segment - KCKUCS Layer 21 : LOB segment operations - KCOCOLFS [kdl2.h] Opcode 1 : Write data into ILOB data block - KDLOPWRI Layer 22 : Tablespace bitmapped file operations - KCOCOTBF [ktfb.h] Opcode 1 : format space header - KTFBHFO Opcode 2 : space header generic redo - KTFBHREDO Opcode 3 : space header undo - KTFBHUNDO Opcode 4 : space bitmap block format - KTFBBFO Opcode 5 : bitmap block generic redo - KTFBBREDO Layer 23 : write behind logging of blocks - KCOCOLWR [kcbb.h] Opcode 1 : Dummy block written callback - KCBBLWR Layer 24 : Logminer related (DDL or OBJV# redo) - KCOCOKRV [krv.h] Opcode : common portion of the ddl - KRVDDL Opcode : direct load redo - KRVDLR Opcode : lob related info - KRVLOB Opcode : misc info - KRVMISC Opcode : user info - KRVUSER 还有begin backup时是18.1 end backup 是17.1 nologging操作是19.2 并注明是invld