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[KOR] ODI no.004 analysis of oracle performance degradation caused by inefficient block cleanout

EXEM
EXEM

The document presents an internal analysis report by Exem Co., Ltd. on Oracle performance degradation due to inefficient block cleanout. It covers transaction slot before-image chaining, fast and delayed block cleanout techniques, and provides a detailed examination of their architectural implications. Key questions and scenarios involving transaction slots, commit SCN, and resource limitations are discussed to address performance issues in large Oracle sites.

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© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Research & Contents Team Analysis of Oracle Performance Degradation caused by Inefficient block cleanout Oracle Deep Internal report no. 004 (2016.05.20)
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅰ. Transaction slot Before-image Chaining Ⅰ-1. Questions Ⅰ-2. Architecture of transaction slot before-image chaining Ⅰ-3. Flow chart of delayed block cleanout Ⅱ. Block cleanout Analysis Ⅱ-1. Fast block cleanout (Fast commit) Ⅱ-2. Delayed block cleanout using “commit SCN” of transaction slot Ⅱ-3. Efficient Delayed Block Cleanout (Delayed block cleanout using “commit SCN” of TRN CTL) Ⅱ-4. Inefficient Delayed Block Cleanout (Delayed block cleanout using ”commit SCN” of transaction slot before-image chaining) Table of Agenda
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅰ. Transaction slot Before-image Chaining Oracle Deep Internal
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅰ-1. Questions Select 시 db file sequential read가 반복적으로 수행되는 wait 현상이 대형 오라클 사이트에서 빈번하게 발생 Undo file Undo block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Transaction slot의 commit scn을 data block itl의 scn/fsc 컬럼에 update 하는 것 Data blockData block Cleanout 이란 무엇인가? Question 1 BH (0x643fa1c8) file#: 5 rdba: 0x0140dcad (5/56493) class: 1 ba: 0x643b6000 st: XCURRENT md: EXCL fpin: 'kdswh11: kdst_fetch' tch: 1 Itl Xid Uba Flag Lck Scn/Fsc 0x01 0x000a.000.00000534 0x018000d2.01e6.01 C--- 0 scn 0x0000.003dbe3a 0x02 0x0007.000.000004ed 0x018000a2.01d5.01 ---- 1 fsc 0x0000.00000000 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 BH (0x643fa1c8) file#: 5 rdba: 0x0140dcad (5/56493) class: 1 ba: 0x643b6000 st: XCURRENT md: EXCL fpin: 'kdswh11: kdst_fetch' tch: 1 Itl Xid Uba Flag Lck Scn/Fsc 0x01 0x000a.000.00000534 0x018000d2.01e6.01 C--- 0 scn 0x0000.003dbe3a 0x02 0x0007.000.000004ed 0x018000a2.01d5.01 --U- 1 fsc 0x0000.003dbe4e tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Undo Header index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------- 0x00 10 0x80 0x04ed 0x0000 0x0000.003dbe4e 0x018000a2 0x01 9 0x00 0x04ec 0x0002 0x0000.003d6d72 0x00000000 0x02 9 0x00 0x04ec 0x0003 0x0000.003d6d72 0x00000000 트랜잭션 상태 Cleanout 상태 Answer 1 Ⅰ-1. Questions Commit scn Commit scn 적용 전 Commit scn 적용 후 Transaction 상태
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 순식간에 완료된다. • 일부만 cleanout 하고 나중에 cleanout하기 때문에 시간이 적게 소요된다. 만약 100억 건을 update 한 후에 Commit을 한다면, 100억 건에 대해서 모두 완료하기까지 시간이 얼마나 소요될까? Question 2 Answer 2 Ⅰ-1. Questions
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Undo는 제한된 자원이기 때문에 트랜잭션 슬롯은 overwrite이 된다. 나중에 사용하기 위해서 저장하고 있던 commit scn은 어떻게 될까? Question 3 • Undo는 제한적인 자원이기 때문에 영원히 보관할 수 없고, 시간이 지나 면 aging out 된다. • Undo slot의 before image가 chaining 되면서 저장된다. • 뒤의 슬라이드 참조 Answer 3 Ⅰ-1. Questions
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff index state cflags wrap# uel scn dba ------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c rdba: 0x01800160 (6/352) TRN CTL seq: 0x0485 chd: 0x0005 ctl: 0x0006 uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 10 0x80 0x0ad7 0xffff 0x0000.0022c821 0x0180011f UNDO BLK rdba: 0x0180011e seq: 0x485 Rec # 0x2 slt: 0x06 xid: 0x0001.006.00000ad7 uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811 chd 0x0006 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x06 slot SCN이 before image로 저장 Ⅰ-2. Architecture of transaction slot before image chaining (1/3) • Chd: chain header 링크드 리스트의 시작, 다음 번 트랜잭션이 사용할 트랜잭션 테이블 슬롯 • Ctl: chain tail 링크드 리스트의 끝, 해언당 두 세그먼트에서 마지막으로 사용한 트랜잭션 테 이블 슬롯 0x06 슬롯 갱신 (state 10, cflags 0x80, SCN 갱신) 1 3 rdba: 0x0180011e (6/286) rdba: 0x01800160 (6/352) Update된 undo header block은 TRN CTL uba에 before image의 위치를 기록하고, SCN에 이전 슬롯의 SCN을 기록 2 file#=6 block#=352 1 1 2 2 1
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff index state cflags wrap# uel scn dba ------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c TRN CTL seq: 0x0485 chd: 0x0005 ctl: 0x0006 uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f rdba: 0x0180011e (6/286) UNDO BLK rdba: 0x0180011e seq: 0x485 Rec # 0x2 slt: 0x06 xid: 0x0001.006.00000ad7 uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811rdba: 0x0180011f (6/287) UNDO BLK rdba: 0x0180011f seq: 0x485 Rec # 0x2 slt: 0x05 xid: 0x0001.006.00000ad7 uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022c811 prv tx scn: 0x0000.0022c818 TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011f.0485.02 scn: 0x0000.0022c818 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 10 0x80 0x0ad5 0xffff 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad7 0x0005 0x0000.0022c821 0x0180011f 0x05 슬롯 갱신 (state 10, cflags 0x80, SCN 갱신) Ⅰ-2. Architecture of transaction slot before image chaining (2/3) 3 rdba: 0x01800160 (6/352) rdba: 0x01800160 (6/352) chd 0x0005 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x05 slot SCN이 before image로 저장 1 rdba: 0x01800160 (6/352) Update된 undo header block은 TRN CTL uba에 before image의 위치를 기록하고, SCN에 이전 슬롯의 SCN을 기록 2 1 1 1 2 2
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff index state cflags wrap# uel scn dba ------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c TRN CTL seq: 0x0485 chd: 0x0005 ctl: 0x0006 uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f UNDO BLK rdba: 0x0180011e seq: 0x485 Rec # 0x2 slt: 0x06 xid: 0x0001.006.00000ad7 uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811 UNDO BLK rdba: 0x0180011f seq: 0x485 Rec # 0x2 slt: 0x05 xid: 0x0001.006.00000ad7 uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022c811 prv tx scn: 0x0000.0022c818 TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011f.0485.02 scn: 0x0000.0022c818 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0xffff 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad7 0x0005 0x0000.0022c821 0x0180011f TRN CTL seq: 0x0486 chd: 0x0005 ctl: 0x0006 uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 10 0x80 0x0ad8 0xffff 0x0000.0022c832 0x01800121 UNDO BLK rdba: 0x01800120 seq: 0x486 Rec # 0x2 slt: 0x06 xid: 0x0001.005.00000ad5 uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821 0x06 슬롯 갱신 (state 10, cflags 0x80, SCN 갱신) Ⅰ-2. Architecture of transaction slot before image chaining (3/3) 3 Endless loop.. rdba: 0x01800160 (6/352) rdba: 0x01800160 (6/352) rdba: 0x01800160 (6/352) rdba: 0x01800160 (6/352) rdba: 0x0180011e (6/286) rdba: 0x0180011f (6/287) rdba: 0x01800120 (6/288) chd 0x0006 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x06 slot SCN이 before image로 저장 Update된 undo header block은 TRN CTL uba에 before image의 위치를 기록하고, SCN에 이전 슬롯의 SCN을 기록 1 2 1 1 1 2 2
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. YES NO NO YES YES NO Wrap 번호가 같은가? Before-image SCN이 Query SCN보다 최신인가? TRN CTL SCN 적용 이전 이미지 SCN과 비교 반복 수행 해당 SCN 적용 해당 SCN 적용 <Delayed Block cleanout 작업> Efficient delayed block cleanout Inefficient delayed block cleanout delayed block cleanout using “commit SCN” of transaction slot Ⅰ-3. Flow chart of delayed block cleanout Query SCN이 TRN CTL SCN보다 최신인가?
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅰ-3. Flow chart of delayed block cleanout <Inefficient delayed block cleanout> Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022d821 index state cflags wrap# uel scn dba --------------------------------------------------------------------------------------- -- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022d829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022d832 0x01800121 Undo Block buffer tsn: 6 rdba: 0x01800120 (6/288) UNDO BLK: xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022d818 prv tx scn: 0x0000.0022d821 txn start scn: scn: 0x0000.0022d831 logon user: 5 prev brb: 25166111 prev bcl: 0 Undo Block buffer tsn: 6 rdba: 0x0180011f (6/287) UNDO BLK: xid: 0x0001.006.00000ad7 seq: 0x485 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x05 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022d811 prv tx scn: 0x0000.0022d818 txn start scn: scn: 0x0000.0022d828 logon user: 5 prev brb: 25166110 prev bcl: 0 1 2 3 4 Wrap 번호 비교 TRN CTL SCN을 Query SCN과 비교 Before image SCN을 Query SCN과 비교 해당 before image SCN으로 적용 NO NO NO Wrap 번호가 같은가? Query SCN이 TRN CTL SCN보다 최신인가? Before-image SCN이 Query SCN보다 최신인가? 해당 SCN 적용 0x0ad6 ≠0x0ad8 • Query SCN: 0x0000.0022d811 • Wrap#: 0x0ad6 (itl의 xid) 1 2 3 4 d811 < d821 Query SCN TRN CTL SCN d811 < d818 Query SCN TRN CTL SCN d811 ≥ d811 Query SCN TRN CTL SCN
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Oracle Deep Internal Ⅱ. Block cleanout 분석
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-1. Fast block cleanout (Fast commit) Oracle Deep Internal
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Commit SCN ↓ 9 (Committed) 10 (Active) 0x01 0x0008.013. 000018a8 1--U- Commit SCN (Base#) 0x13 0x008004f8 0x008004f8. 00cf.06 버퍼 캐시의 10% 초과하지 않는 블록들은 세션 메모리 내에 리스트로 생성 Fast block cleanout은 “트랜잭션이 종료되는 시점에 Dirty블록에 관련된 트랜잭션의 정보를 정리하는 작업” 0x18a8 Ⅱ-1. Fast block cleanout (Fast commit)
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Oracle Deep Internal Ⅱ-2. Delayed block cleanout using “commit SCN” of transaction slot
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-2. Delayed block cleanout using “commit SCN” of transaction slot Delayed block cleanout은 “커밋 시점에 클린아웃 되지 않은 블록들(변경 하려는 블록의 수가 버퍼 캐시의 10%를 초과), 메모리에서 flush되어 cleanout 처리되지 않고 datafile에 기록된 블록들을 다음 세션에 의해 클린아웃 작업” 0x13 0x0080006c 0x01 0C--- Commit SCN0x008004f8 00cf.06 9 (Committed) Commit SCN0x18a8 0x0008.013. 000018a8 Row Lock Delayed block cleanout을 수행하는 세션은 클린아웃 되지 않은 트랜잭션의 xid를 이용해 undo header block의 transaction table을 확인(트랜잭션 종료여부, SCN)후, 해당 block header의 ITL에 Lock byte 해제, SCN 설정, Flag를 C---로 변경 후 이에 대한 redo log를 생성한다.
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-3. Efficient Delayed Block Cleanout Oracle Deep Internal
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. * Upper bound commit Upper bound commit은 “원래 commit이 일어난 시점의 SCN이어야 하지만 overwrite 되었을 경우, cleanout 할 쿼리 SCN(818)부터 시작해서 원래 commit이 일어난 시점(811)의 SCN 사이에 있는 가장 높은 값을 의미한다” Upper bound commit
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-3. Efficient Delayed Block Cleanout • Undo segment 10개 중 9개 offline, 1개만 online • Undo segment의 34개 슬롯 중 32개 active, 2개만 사용 가능 시나리오 Update Table T1 Flush Buffer Commit Update & Commit Update & Commit Update & Commit Update & Commit Select Table T1 t1 t2 t3 S1 S2Time
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows 1. 초기상태 ITL 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Undo Block Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ ㅁ buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 Undo Header 메모리에 적재
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 chd 0x0014 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x14 slot SCN이 before-image로 저장
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c BH (0x63fe3de8) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63d6e000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b Update된 undo header block은 TRN CTL uba에 before-image의 위치를 기록하 고, SCN에 이전 슬롯의 SCN을 기록 Before image가 있는 Undo Block 0x14 슬롯 갱신 (state, cflag, wrap#, scn)
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 BH (0x63fe3de8) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63d6e000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ Rows ITL block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fscItl Xid Uba Flag Lck Scn/fsc
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 BH (0x63fe3de8) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63d6e000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ Rows ITL block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ASCII code 42 => Value ‘B’
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 3. alter system flush buffer_cache ; Undo Header Undo Block buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 flush Itl Xid Uba Flag Lck Scn/fsc
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 4. commit; BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0x0014 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353b 0xffff 0x0000.006e8efd 0x0180011b Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header Undo Block buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 Itl Xid Uba Flag Lck Scn/fsc
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 5. Undo Header Slot 재사용 (세션2에서 Update 첫 번째) Undo Block Undo Header Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 2 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0014 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.32 scn: 0x0000.006e8ee4 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 10 0x80 0x3539 0x0005 0x0000.006e8f05 0x0180011d 0x14 9 0x00 0x353b 0xffff 0x0000.006e8efd 0x0180011b buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011d (6/285) UNDO BLK: xid: 0x0006.004.00003539 seq: 0x1cc1 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x04 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 41 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit;
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 6. Undo Header Slot 재사용 (세션2에서 Update 두 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 2 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011d.1cc1.02 scn: 0x0000.006e8efd … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3539 0xffff 0x0000.006e8f06 0x0180011d 0x14 10 0x80 0x353c 0x0005 0x0000.006e8f0d 0x0180011e buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011e (6/286) UNDO BLK: xid: 0x0006.014.0000353c seq: 0x1cc1 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 50 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit;
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 7. Undo Header Slot 재사용 (세션2에서 Update 세 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 2 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0014 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011e.1cc1.02 scn: 0x0000.006e8f06 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 10 0x80 0x353a 0x0005 0x0000.006e8f15 0x0180011f 0x14 9 0x00 0x353c 0xffff 0x0000.006e8f0e 0x0180011e buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011f (6/287) UNDO BLK: xid: 0x0006.004.0000353a seq: 0x1cc1 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x04 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 51 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit;
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 8. Undo Header Slot 재사용 (세션2에서 Update 네 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 3 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0xffff 0x0000.006e8f16 0x0180011f 0x14 10 0x80 0x353d 0x0005 0x0000.006e8f1c 0x01800130 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x01800130 (6/304) UNDO BLK: xid: 0x0006.014.0000353d seq: 0x1cc2 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 52 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit;
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x647efe78) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x646aa000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f 0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130 9. select /*+ full(t1) */count(*) from t1 where rownum <= 1; 현재 시점 undo header block 의 TRN CTL SCN 값으로 cleanout BH (0x657f85c0) file#: 5 rdba: 0x01418413 (5/99347) class: 1 ba: 0x65788000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x01418413 (5/99347) … 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 C-U- 0 scn 0x0000.006e8f0e 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f 0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130 buffer tsn: 6 rdba: 0x01800130 (6/304) UNDO BLK: xid: 0x0006.014.0000353d seq: 0x1cc2 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 52 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc ASCII code 42 => Value ‘B’ Begin cleaning out block ... Block header dump: 0x01418413 … Itl Xid Uba Flag Lck Scn/Fsc 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #139971596639184: nam='db file sequential read' ela= 15 file#=6 block#=288 blocks=1 obj#=0 tim=1460423039184663 … Block cleanout record, scn: 0xffff.ffffffff ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.006e8f0e Block header dump: 0x01418413 … Itl Xid Uba Flag Lck Scn/Fsc 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 C-U- 0 scn 0x0000.006e8f0e 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo header Block
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x647efe78) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x646aa000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f 0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130 9. select /*+ full(t1) */count(*) from t1 where rownum <= 1; 현재 시점 undo header block 의 TRN CTL SCN 값으로 cleanout. BH (0x657f85c0) file#: 5 rdba: 0x01418413 (5/99347) class: 1 ba: 0x65788000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x01418413 (5/99347) … 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 C-U- 0 scn 0x0000.006e8f0e 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f 0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130 buffer tsn: 6 rdba: 0x01800130 (6/304) UNDO BLK: xid: 0x0006.014.0000353d seq: 0x1cc2 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 52 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc ASCII code 42 => Value ‘B’
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-4. Inefficient Delayed Block Cleanout Oracle Deep Internal
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-4. Inefficient delayed block cleanout • Undo segment 10개 중 9개 offline, 1개만 online • Undo segment의 34개 슬롯 중 32개 active, 2개만 사용 가능 시나리오 Update Table T1 Flush Buffer Commit Select Table T1 t1 t2 t4 S1 S2Time t3 Update & Commit Update & Commit Update & Commit Update & Commit Set transaction read only
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 1. 초기상태 ITL 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c ASCII code 41 => Value ‘A’ Undo Block Itl Xid Uba Flag Lck Scn/fsc
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Undo Header 메모리에 적재 Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c chd 0x0006 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x06 slot SCN이 before-mage로 저장
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc BH (0x663ea0a0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66210000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Before image가 있는 Undo Block Update된 undo header block은 TRN CTL uba에 before-image의 위치를 기록하 고, SCN에 이전 슬롯의 SCN을 기록 0x06 슬롯 갱신 (state, cflag, wrap#, scn)
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc BH (0x663ea0a0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66210000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc BH (0x663ea0a0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66210000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ASCII code 42 => Value ‘B’
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 3. alter system flush buffer_cache ; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 flush Itl Xid Uba Flag Lck Scn/fsc
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 4. commit; Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c BH (0x66be9f68) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66a0e000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0x0006 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad6 0xffff 0x0000.0022c811 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 Itl Xid Uba Flag Lck Scn/fsc
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 5. Set transaction read only ; Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 Itl Xid Uba Flag Lck Scn/fsc <Read only 시점> • 현재 세션 Commit 시점 이후 (0x0000.0022c811 ) • 다른 세션 Commit 시점 이전 (0x0000.0022c818)
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 6. Undo Header Slot 재사용 (세션2에서 Update 첫 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header Itl Xid Uba Flag Lck Scn/fsc ASCII code 42 => Value ‘B’ Session2> Update t2 set col2=‘B’; Session2> Commit; buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.005.00000ad4 seq: 0x485 cnt: 0x32 irb: 0x32 icl: 0x0 flg: 0x0000 * Rec #0x31 slt: 0x05 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.09 ctl max scn: 0x0000.0022c7fe prv tx scn: 0x0000.0022c7ff txn start scn: scn: 0x0000.0022c816 logon user: 5 prev brb: 25166109 prev bcl: 0
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 7. Undo Header Slot 재사용 (세션2에서 Update 두 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header Itl Xid Uba Flag Lck Scn/fsc ASCII code 42 => Value ‘B’ Session2> Update t2 set col2=‘B’; Session2> Commit; buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f buffer tsn: 6 rdba: 0x0180011e (6/286) UNDO BLK: xid: 0x0001.006.00000ad7 seq: 0x485 cnt: 0x3 irb: 0x3 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811 txn start scn: scn: 0x0000.0022c820 logon user: 5 prev brb: 25166108 prev bcl: 0
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 8. Undo Header Slot 재사용 (세션2에서 Update 세 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit; buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.0485.02 scn: 0x0000.0022c818 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0xffff 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad7 0x0005 0x0000.0022c821 0x0180011f buffer tsn: 6 rdba: 0x0180011f (6/287) UNDO BLK: xid: 0x0001.006.00000ad7 seq: 0x485 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x05 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022c811 prv tx scn: 0x0000.0022c818 txn start scn: scn: 0x0000.0022c828 logon user: 5 prev brb: 25166110 prev bcl: 0
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 9. Undo Header Slot 재사용 (세션2에서 Update 네 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit; buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 buffer tsn: 6 rdba: 0x01800120 (6/288) UNDO BLK: xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821 txn start scn: scn: 0x0000.0022c831 logon user: 5 prev brb: 25166111 prev bcl: 0
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x623e85d0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x621e4000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 0 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 … index state cflags wrap# uel scn dba ----------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 10. select /*+ full(t1) */count(*) from t1 where rownum <= 1; undo header block 의 CR을 만드는 과정에서 undo block read 발생함. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x01800121 (6/289) UNDO BLK: xid: 0x0001.006.00000ad8 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 BH (0x66bf7720) file#: 5 rdba: 0x014000e3 (5/227) class: 1 ba: 0x66b70000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x014000e3 (5/227) … 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc Begin cleaning out block ... Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224 WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417 WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687 … Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.0022c811 Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undoheader Block 두 번째 update Undo Block 첫 번째 update Undo Block BH (0x673f4b40) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x67328000 st: CR md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f Begin cleaning out block ... Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224 WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417 WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687 … Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.0022c811 Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo header Block 두 번째 update Undo Block 첫 번째 update Undo Block
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x623e85d0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x621e4000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 0 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 … index state cflags wrap# uel scn dba ----------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 10. select /*+ full(t1) */count(*) from t1 where rownum <= 1; undo header block 의 CR을 만드는 과정에서 undo block read 발생함. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x66bf7720) file#: 5 rdba: 0x014000e3 (5/227) class: 1 ba: 0x66b70000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x014000e3 (5/227) … 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 buffer tsn: 6 rdba: 0x01800120 (6/288) UNDO BLK: xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821 txn start scn: scn: 0x0000.0022c831 logon user: 5 prev brb: 25166111 prev bcl: 0 Begin cleaning out block ... Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224 WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417 WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687 … Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.0022c811 Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo header Block 두 번째 update Undo Block 첫 번째 update Undo Block Scn: 0x0000.0022c821 Scn: 0x0000.0022c818 Scn: 0x0000.0022c811
SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x623e85d0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x621e4000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 0 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 … index state cflags wrap# uel scn dba ----------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 10. select /*+ full(t1) */count(*) from t1 where rownum <= 1; undo header block 의 CR을 만드는 과정에서 undo block read 발생함. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x66bf7720) file#: 5 rdba: 0x014000e3 (5/227) class: 1 ba: 0x66b70000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x014000e3 (5/227) … 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 buffer tsn: 6 rdba: 0x01800120 (6/288) UNDO BLK: xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821 txn start scn: scn: 0x0000.0022c831 logon user: 5 prev brb: 25166111 prev bcl: 0 Begin cleaning out block ... Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224 WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417 WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687 … Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.0022c811 Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo header Block 두 번째 update Undo Block 첫 번째 update Undo Block BH (0x673f4b40) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x67328000 st: CR md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f Scn: 0x0000.0022c821 Scn: 0x0000.0022c818 Scn: 0x0000.0022c811 CR 블록 적용
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[KOR] ODI no.004 analysis of oracle performance degradation caused by inefficient block cleanout

  • 1. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Research & Contents Team Analysis of Oracle Performance Degradation caused by Inefficient block cleanout Oracle Deep Internal report no. 004 (2016.05.20)
  • 2. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
  • 3. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅰ. Transaction slot Before-image Chaining Ⅰ-1. Questions Ⅰ-2. Architecture of transaction slot before-image chaining Ⅰ-3. Flow chart of delayed block cleanout Ⅱ. Block cleanout Analysis Ⅱ-1. Fast block cleanout (Fast commit) Ⅱ-2. Delayed block cleanout using “commit SCN” of transaction slot Ⅱ-3. Efficient Delayed Block Cleanout (Delayed block cleanout using “commit SCN” of TRN CTL) Ⅱ-4. Inefficient Delayed Block Cleanout (Delayed block cleanout using ”commit SCN” of transaction slot before-image chaining) Table of Agenda
  • 4. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅰ. Transaction slot Before-image Chaining Oracle Deep Internal
  • 5. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅰ-1. Questions Select 시 db file sequential read가 반복적으로 수행되는 wait 현상이 대형 오라클 사이트에서 빈번하게 발생 Undo file Undo block
  • 6. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Transaction slot의 commit scn을 data block itl의 scn/fsc 컬럼에 update 하는 것 Data blockData block Cleanout 이란 무엇인가? Question 1 BH (0x643fa1c8) file#: 5 rdba: 0x0140dcad (5/56493) class: 1 ba: 0x643b6000 st: XCURRENT md: EXCL fpin: 'kdswh11: kdst_fetch' tch: 1 Itl Xid Uba Flag Lck Scn/Fsc 0x01 0x000a.000.00000534 0x018000d2.01e6.01 C--- 0 scn 0x0000.003dbe3a 0x02 0x0007.000.000004ed 0x018000a2.01d5.01 ---- 1 fsc 0x0000.00000000 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 BH (0x643fa1c8) file#: 5 rdba: 0x0140dcad (5/56493) class: 1 ba: 0x643b6000 st: XCURRENT md: EXCL fpin: 'kdswh11: kdst_fetch' tch: 1 Itl Xid Uba Flag Lck Scn/Fsc 0x01 0x000a.000.00000534 0x018000d2.01e6.01 C--- 0 scn 0x0000.003dbe3a 0x02 0x0007.000.000004ed 0x018000a2.01d5.01 --U- 1 fsc 0x0000.003dbe4e tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Undo Header index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------- 0x00 10 0x80 0x04ed 0x0000 0x0000.003dbe4e 0x018000a2 0x01 9 0x00 0x04ec 0x0002 0x0000.003d6d72 0x00000000 0x02 9 0x00 0x04ec 0x0003 0x0000.003d6d72 0x00000000 트랜잭션 상태 Cleanout 상태 Answer 1 Ⅰ-1. Questions Commit scn Commit scn 적용 전 Commit scn 적용 후 Transaction 상태
  • 7. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 순식간에 완료된다. • 일부만 cleanout 하고 나중에 cleanout하기 때문에 시간이 적게 소요된다. 만약 100억 건을 update 한 후에 Commit을 한다면, 100억 건에 대해서 모두 완료하기까지 시간이 얼마나 소요될까? Question 2 Answer 2 Ⅰ-1. Questions
  • 8. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Undo는 제한된 자원이기 때문에 트랜잭션 슬롯은 overwrite이 된다. 나중에 사용하기 위해서 저장하고 있던 commit scn은 어떻게 될까? Question 3 • Undo는 제한적인 자원이기 때문에 영원히 보관할 수 없고, 시간이 지나 면 aging out 된다. • Undo slot의 before image가 chaining 되면서 저장된다. • 뒤의 슬라이드 참조 Answer 3 Ⅰ-1. Questions
  • 9. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff index state cflags wrap# uel scn dba ------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c rdba: 0x01800160 (6/352) TRN CTL seq: 0x0485 chd: 0x0005 ctl: 0x0006 uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 10 0x80 0x0ad7 0xffff 0x0000.0022c821 0x0180011f UNDO BLK rdba: 0x0180011e seq: 0x485 Rec # 0x2 slt: 0x06 xid: 0x0001.006.00000ad7 uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811 chd 0x0006 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x06 slot SCN이 before image로 저장 Ⅰ-2. Architecture of transaction slot before image chaining (1/3) • Chd: chain header 링크드 리스트의 시작, 다음 번 트랜잭션이 사용할 트랜잭션 테이블 슬롯 • Ctl: chain tail 링크드 리스트의 끝, 해언당 두 세그먼트에서 마지막으로 사용한 트랜잭션 테 이블 슬롯 0x06 슬롯 갱신 (state 10, cflags 0x80, SCN 갱신) 1 3 rdba: 0x0180011e (6/286) rdba: 0x01800160 (6/352) Update된 undo header block은 TRN CTL uba에 before image의 위치를 기록하고, SCN에 이전 슬롯의 SCN을 기록 2 file#=6 block#=352 1 1 2 2 1
  • 10. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff index state cflags wrap# uel scn dba ------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c TRN CTL seq: 0x0485 chd: 0x0005 ctl: 0x0006 uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f rdba: 0x0180011e (6/286) UNDO BLK rdba: 0x0180011e seq: 0x485 Rec # 0x2 slt: 0x06 xid: 0x0001.006.00000ad7 uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811rdba: 0x0180011f (6/287) UNDO BLK rdba: 0x0180011f seq: 0x485 Rec # 0x2 slt: 0x05 xid: 0x0001.006.00000ad7 uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022c811 prv tx scn: 0x0000.0022c818 TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011f.0485.02 scn: 0x0000.0022c818 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 10 0x80 0x0ad5 0xffff 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad7 0x0005 0x0000.0022c821 0x0180011f 0x05 슬롯 갱신 (state 10, cflags 0x80, SCN 갱신) Ⅰ-2. Architecture of transaction slot before image chaining (2/3) 3 rdba: 0x01800160 (6/352) rdba: 0x01800160 (6/352) chd 0x0005 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x05 slot SCN이 before image로 저장 1 rdba: 0x01800160 (6/352) Update된 undo header block은 TRN CTL uba에 before image의 위치를 기록하고, SCN에 이전 슬롯의 SCN을 기록 2 1 1 1 2 2
  • 11. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff index state cflags wrap# uel scn dba ------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c TRN CTL seq: 0x0485 chd: 0x0005 ctl: 0x0006 uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f UNDO BLK rdba: 0x0180011e seq: 0x485 Rec # 0x2 slt: 0x06 xid: 0x0001.006.00000ad7 uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811 UNDO BLK rdba: 0x0180011f seq: 0x485 Rec # 0x2 slt: 0x05 xid: 0x0001.006.00000ad7 uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022c811 prv tx scn: 0x0000.0022c818 TRN CTL seq: 0x0485 chd: 0x0006 ctl: 0x0005 uba: 0x0180011f.0485.02 scn: 0x0000.0022c818 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0xffff 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad7 0x0005 0x0000.0022c821 0x0180011f TRN CTL seq: 0x0486 chd: 0x0005 ctl: 0x0006 uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba -------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 10 0x80 0x0ad8 0xffff 0x0000.0022c832 0x01800121 UNDO BLK rdba: 0x01800120 seq: 0x486 Rec # 0x2 slt: 0x06 xid: 0x0001.005.00000ad5 uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821 0x06 슬롯 갱신 (state 10, cflags 0x80, SCN 갱신) Ⅰ-2. Architecture of transaction slot before image chaining (3/3) 3 Endless loop.. rdba: 0x01800160 (6/352) rdba: 0x01800160 (6/352) rdba: 0x01800160 (6/352) rdba: 0x01800160 (6/352) rdba: 0x0180011e (6/286) rdba: 0x0180011f (6/287) rdba: 0x01800120 (6/288) chd 0x0006 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x06 slot SCN이 before image로 저장 Update된 undo header block은 TRN CTL uba에 before image의 위치를 기록하고, SCN에 이전 슬롯의 SCN을 기록 1 2 1 1 1 2 2
  • 12. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. YES NO NO YES YES NO Wrap 번호가 같은가? Before-image SCN이 Query SCN보다 최신인가? TRN CTL SCN 적용 이전 이미지 SCN과 비교 반복 수행 해당 SCN 적용 해당 SCN 적용 <Delayed Block cleanout 작업> Efficient delayed block cleanout Inefficient delayed block cleanout delayed block cleanout using “commit SCN” of transaction slot Ⅰ-3. Flow chart of delayed block cleanout Query SCN이 TRN CTL SCN보다 최신인가?
  • 13. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅰ-3. Flow chart of delayed block cleanout <Inefficient delayed block cleanout> Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022d821 index state cflags wrap# uel scn dba --------------------------------------------------------------------------------------- -- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022d829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022d832 0x01800121 Undo Block buffer tsn: 6 rdba: 0x01800120 (6/288) UNDO BLK: xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022d818 prv tx scn: 0x0000.0022d821 txn start scn: scn: 0x0000.0022d831 logon user: 5 prev brb: 25166111 prev bcl: 0 Undo Block buffer tsn: 6 rdba: 0x0180011f (6/287) UNDO BLK: xid: 0x0001.006.00000ad7 seq: 0x485 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x05 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022d811 prv tx scn: 0x0000.0022d818 txn start scn: scn: 0x0000.0022d828 logon user: 5 prev brb: 25166110 prev bcl: 0 1 2 3 4 Wrap 번호 비교 TRN CTL SCN을 Query SCN과 비교 Before image SCN을 Query SCN과 비교 해당 before image SCN으로 적용 NO NO NO Wrap 번호가 같은가? Query SCN이 TRN CTL SCN보다 최신인가? Before-image SCN이 Query SCN보다 최신인가? 해당 SCN 적용 0x0ad6 ≠0x0ad8 • Query SCN: 0x0000.0022d811 • Wrap#: 0x0ad6 (itl의 xid) 1 2 3 4 d811 < d821 Query SCN TRN CTL SCN d811 < d818 Query SCN TRN CTL SCN d811 ≥ d811 Query SCN TRN CTL SCN
  • 14. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Oracle Deep Internal Ⅱ. Block cleanout 분석
  • 15. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-1. Fast block cleanout (Fast commit) Oracle Deep Internal
  • 16. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Commit SCN ↓ 9 (Committed) 10 (Active) 0x01 0x0008.013. 000018a8 1--U- Commit SCN (Base#) 0x13 0x008004f8 0x008004f8. 00cf.06 버퍼 캐시의 10% 초과하지 않는 블록들은 세션 메모리 내에 리스트로 생성 Fast block cleanout은 “트랜잭션이 종료되는 시점에 Dirty블록에 관련된 트랜잭션의 정보를 정리하는 작업” 0x18a8 Ⅱ-1. Fast block cleanout (Fast commit)
  • 17. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Oracle Deep Internal Ⅱ-2. Delayed block cleanout using “commit SCN” of transaction slot
  • 18. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-2. Delayed block cleanout using “commit SCN” of transaction slot Delayed block cleanout은 “커밋 시점에 클린아웃 되지 않은 블록들(변경 하려는 블록의 수가 버퍼 캐시의 10%를 초과), 메모리에서 flush되어 cleanout 처리되지 않고 datafile에 기록된 블록들을 다음 세션에 의해 클린아웃 작업” 0x13 0x0080006c 0x01 0C--- Commit SCN0x008004f8 00cf.06 9 (Committed) Commit SCN0x18a8 0x0008.013. 000018a8 Row Lock Delayed block cleanout을 수행하는 세션은 클린아웃 되지 않은 트랜잭션의 xid를 이용해 undo header block의 transaction table을 확인(트랜잭션 종료여부, SCN)후, 해당 block header의 ITL에 Lock byte 해제, SCN 설정, Flag를 C---로 변경 후 이에 대한 redo log를 생성한다.
  • 19. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-3. Efficient Delayed Block Cleanout Oracle Deep Internal
  • 20. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. * Upper bound commit Upper bound commit은 “원래 commit이 일어난 시점의 SCN이어야 하지만 overwrite 되었을 경우, cleanout 할 쿼리 SCN(818)부터 시작해서 원래 commit이 일어난 시점(811)의 SCN 사이에 있는 가장 높은 값을 의미한다” Upper bound commit
  • 21. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-3. Efficient Delayed Block Cleanout • Undo segment 10개 중 9개 offline, 1개만 online • Undo segment의 34개 슬롯 중 32개 active, 2개만 사용 가능 시나리오 Update Table T1 Flush Buffer Commit Update & Commit Update & Commit Update & Commit Update & Commit Select Table T1 t1 t2 t3 S1 S2Time
  • 22. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows 1. 초기상태 ITL 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Undo Block Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’
  • 23. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ ㅁ buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 Undo Header 메모리에 적재
  • 24. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 chd 0x0014 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x14 slot SCN이 before-image로 저장
  • 25. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c BH (0x63fe3de8) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63d6e000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b Update된 undo header block은 TRN CTL uba에 before-image의 위치를 기록하 고, SCN에 이전 슬롯의 SCN을 기록 Before image가 있는 Undo Block 0x14 슬롯 갱신 (state, cflag, wrap#, scn)
  • 26. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 BH (0x63fe3de8) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63d6e000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ Rows ITL block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fscItl Xid Uba Flag Lck Scn/fsc
  • 27. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows ITL Undo Block buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 BH (0x63fe3de8) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63d6e000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b 2. update t1 set col2='B'; Undo Header block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c Itl Xid Uba Flag Lck Scn/fsc ASCII code 41 => Value ‘A’ Rows ITL block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ASCII code 42 => Value ‘B’
  • 28. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 3. alter system flush buffer_cache ; Undo Header Undo Block buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 flush Itl Xid Uba Flag Lck Scn/fsc
  • 29. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 4. commit; BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0x0014 0x0000.006e8ee4 0x0180011b 0x14 9 0x00 0x353b 0xffff 0x0000.006e8efd 0x0180011b Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header Undo Block buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011b (6/283) UNDO BLK: xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000 * Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3 txn start scn: scn: 0x0000.006e8efa logon user: 5 prev brb: 25166108 prev bcl: 0 Itl Xid Uba Flag Lck Scn/fsc
  • 30. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 5. Undo Header Slot 재사용 (세션2에서 Update 첫 번째) Undo Block Undo Header Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 2 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0014 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.32 scn: 0x0000.006e8ee4 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 10 0x80 0x3539 0x0005 0x0000.006e8f05 0x0180011d 0x14 9 0x00 0x353b 0xffff 0x0000.006e8efd 0x0180011b buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011d (6/285) UNDO BLK: xid: 0x0006.004.00003539 seq: 0x1cc1 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x04 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 41 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit;
  • 31. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 6. Undo Header Slot 재사용 (세션2에서 Update 두 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 2 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011d.1cc1.02 scn: 0x0000.006e8efd … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3539 0xffff 0x0000.006e8f06 0x0180011d 0x14 10 0x80 0x353c 0x0005 0x0000.006e8f0d 0x0180011e buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011e (6/286) UNDO BLK: xid: 0x0006.014.0000353c seq: 0x1cc1 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 50 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit;
  • 32. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 7. Undo Header Slot 재사용 (세션2에서 Update 세 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 2 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0014 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011e.1cc1.02 scn: 0x0000.006e8f06 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 10 0x80 0x353a 0x0005 0x0000.006e8f15 0x0180011f 0x14 9 0x00 0x353c 0xffff 0x0000.006e8f0e 0x0180011e buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x0180011f (6/287) UNDO BLK: xid: 0x0006.004.0000353a seq: 0x1cc1 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x04 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 51 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit;
  • 33. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 8. Undo Header Slot 재사용 (세션2에서 Update 네 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 3 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0xffff 0x0000.006e8f16 0x0180011f 0x14 10 0x80 0x353d 0x0005 0x0000.006e8f1c 0x01800130 buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b 0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b buffer tsn: 6 rdba: 0x01800130 (6/304) UNDO BLK: xid: 0x0006.014.0000353d seq: 0x1cc2 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 52 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit;
  • 34. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x647efe78) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x646aa000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f 0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130 9. select /*+ full(t1) */count(*) from t1 where rownum <= 1; 현재 시점 undo header block 의 TRN CTL SCN 값으로 cleanout BH (0x657f85c0) file#: 5 rdba: 0x01418413 (5/99347) class: 1 ba: 0x65788000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x01418413 (5/99347) … 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 C-U- 0 scn 0x0000.006e8f0e 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f 0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130 buffer tsn: 6 rdba: 0x01800130 (6/304) UNDO BLK: xid: 0x0006.014.0000353d seq: 0x1cc2 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 52 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc ASCII code 42 => Value ‘B’ Begin cleaning out block ... Block header dump: 0x01418413 … Itl Xid Uba Flag Lck Scn/Fsc 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #139971596639184: nam='db file sequential read' ela= 15 file#=6 block#=288 blocks=1 obj#=0 tim=1460423039184663 … Block cleanout record, scn: 0xffff.ffffffff ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.006e8f0e Block header dump: 0x01418413 … Itl Xid Uba Flag Lck Scn/Fsc 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 C-U- 0 scn 0x0000.006e8f0e 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo header Block
  • 35. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x647efe78) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x646aa000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 1 buffer tsn: 6 rdba: 0x01800120 (6/288) … TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f 0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130 9. select /*+ full(t1) */count(*) from t1 where rownum <= 1; 현재 시점 undo header block 의 TRN CTL SCN 값으로 cleanout. BH (0x657f85c0) file#: 5 rdba: 0x01418413 (5/99347) class: 1 ba: 0x65788000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x01418413 (5/99347) … 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 C-U- 0 scn 0x0000.006e8f0e 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426 0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header buffer tsn: 6 rdba: 0x01800120 (6/288) TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f 0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130 buffer tsn: 6 rdba: 0x01800130 (6/304) UNDO BLK: xid: 0x0006.014.0000353d seq: 0x1cc2 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005) col 1: [2000] 52 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc ASCII code 42 => Value ‘B’
  • 36. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-4. Inefficient Delayed Block Cleanout Oracle Deep Internal
  • 37. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Ⅱ-4. Inefficient delayed block cleanout • Undo segment 10개 중 9개 offline, 1개만 online • Undo segment의 34개 슬롯 중 32개 active, 2개만 사용 가능 시나리오 Update Table T1 Flush Buffer Commit Select Table T1 t1 t2 t4 S1 S2Time t3 Update & Commit Update & Commit Update & Commit Update & Commit Set transaction read only
  • 38. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 1. 초기상태 ITL 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c ASCII code 41 => Value ‘A’ Undo Block Itl Xid Uba Flag Lck Scn/fsc
  • 39. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Undo Header 메모리에 적재 Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
  • 40. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c chd 0x0006 슬롯을 사용할 예정이기 때문에 uba, trn ctl SCN, 0x06 slot SCN이 before-mage로 저장
  • 41. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc BH (0x663ea0a0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66210000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Before image가 있는 Undo Block Update된 undo header block은 TRN CTL uba에 before-image의 위치를 기록하 고, SCN에 이전 슬롯의 SCN을 기록 0x06 슬롯 갱신 (state, cflag, wrap#, scn)
  • 42. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc BH (0x663ea0a0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66210000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc
  • 43. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL ASCII code 41 => Value ‘A’ 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 2. update t1 set col2='B'; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c Itl Xid Uba Flag Lck Scn/fsc BH (0x663ea0a0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66210000 st: XCURRENT md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 41 ITL 0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Itl Xid Uba Flag Lck Scn/fsc block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ASCII code 42 => Value ‘B’
  • 44. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 3. alter system flush buffer_cache ; Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 flush Itl Xid Uba Flag Lck Scn/fsc
  • 45. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 4. commit; Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c BH (0x66be9f68) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66a0e000 st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0x0006 0x0000.0022c7ff 0x0180011d 0x06 9 0x00 0x0ad6 0xffff 0x0000.0022c811 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 Itl Xid Uba Flag Lck Scn/fsc
  • 46. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 5. Set transaction read only ; Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d 0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c Undo Block buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000 * Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe txn start scn: scn: 0x0000.0022c809 logon user: 5 prev brb: 25166108 prev bcl: 0 Itl Xid Uba Flag Lck Scn/fsc <Read only 시점> • 현재 세션 Commit 시점 이후 (0x0000.0022c811 ) • 다른 세션 Commit 시점 이전 (0x0000.0022c818)
  • 47. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 6. Undo Header Slot 재사용 (세션2에서 Update 첫 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header Itl Xid Uba Flag Lck Scn/fsc ASCII code 42 => Value ‘B’ Session2> Update t2 set col2=‘B’; Session2> Commit; buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c buffer tsn: 6 rdba: 0x0180011c (6/284) UNDO BLK: xid: 0x0001.005.00000ad4 seq: 0x485 cnt: 0x32 irb: 0x32 icl: 0x0 flg: 0x0000 * Rec #0x31 slt: 0x05 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.09 ctl max scn: 0x0000.0022c7fe prv tx scn: 0x0000.0022c7ff txn start scn: scn: 0x0000.0022c816 logon user: 5 prev brb: 25166109 prev bcl: 0
  • 48. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 7. Undo Header Slot 재사용 (세션2에서 Update 두 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header Itl Xid Uba Flag Lck Scn/fsc ASCII code 42 => Value ‘B’ Session2> Update t2 set col2=‘B’; Session2> Commit; buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f buffer tsn: 6 rdba: 0x0180011e (6/286) UNDO BLK: xid: 0x0001.006.00000ad7 seq: 0x485 cnt: 0x3 irb: 0x3 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811 txn start scn: scn: 0x0000.0022c820 logon user: 5 prev brb: 25166108 prev bcl: 0
  • 49. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 8. Undo Header Slot 재사용 (세션2에서 Update 세 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit; buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011f.0485.02 scn: 0x0000.0022c818 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0xffff 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad7 0x0005 0x0000.0022c821 0x0180011f buffer tsn: 6 rdba: 0x0180011f (6/287) UNDO BLK: xid: 0x0001.006.00000ad7 seq: 0x485 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x05 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022c811 prv tx scn: 0x0000.0022c818 txn start scn: scn: 0x0000.0022c828 logon user: 5 prev brb: 25166110 prev bcl: 0
  • 50. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. 9. Undo Header Slot 재사용 (세션2에서 Update 네 번째) Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header Itl Xid Uba Flag Lck Scn/fsc Session2> Update t2 set col2=‘B’; Session2> Commit; buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 buffer tsn: 6 rdba: 0x01800120 (6/288) UNDO BLK: xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821 txn start scn: scn: 0x0000.0022c831 logon user: 5 prev brb: 25166111 prev bcl: 0
  • 51. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x623e85d0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x621e4000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 0 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 … index state cflags wrap# uel scn dba ----------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 10. select /*+ full(t1) */count(*) from t1 where rownum <= 1; undo header block 의 CR을 만드는 과정에서 undo block read 발생함. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block buffer tsn: 6 rdba: 0x01800121 (6/289) UNDO BLK: xid: 0x0001.006.00000ad8 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x1 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) Undo Header buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 BH (0x66bf7720) file#: 5 rdba: 0x014000e3 (5/227) class: 1 ba: 0x66b70000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x014000e3 (5/227) … 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc Begin cleaning out block ... Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224 WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417 WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687 … Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.0022c811 Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undoheader Block 두 번째 update Undo Block 첫 번째 update Undo Block BH (0x673f4b40) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x67328000 st: CR md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f Begin cleaning out block ... Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224 WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417 WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687 … Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.0022c811 Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo header Block 두 번째 update Undo Block 첫 번째 update Undo Block
  • 52. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x623e85d0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x621e4000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 0 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 … index state cflags wrap# uel scn dba ----------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 10. select /*+ full(t1) */count(*) from t1 where rownum <= 1; undo header block 의 CR을 만드는 과정에서 undo block read 발생함. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x66bf7720) file#: 5 rdba: 0x014000e3 (5/227) class: 1 ba: 0x66b70000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x014000e3 (5/227) … 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 buffer tsn: 6 rdba: 0x01800120 (6/288) UNDO BLK: xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821 txn start scn: scn: 0x0000.0022c831 logon user: 5 prev brb: 25166111 prev bcl: 0 Begin cleaning out block ... Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224 WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417 WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687 … Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.0022c811 Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo header Block 두 번째 update Undo Block 첫 번째 update Undo Block Scn: 0x0000.0022c821 Scn: 0x0000.0022c818 Scn: 0x0000.0022c811
  • 53. SGA Undo SegmentData Block © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. BH (0x623e85d0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x621e4000 st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 0 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 … index state cflags wrap# uel scn dba ----------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 10. select /*+ full(t1) */count(*) from t1 where rownum <= 1; undo header block 의 CR을 만드는 과정에서 undo block read 발생함. Rows block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x2 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 ITL ASCII code 42 => Value ‘B’ 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo Block Undo Header BH (0x66bf7720) file#: 5 rdba: 0x014000e3 (5/227) class: 1 ba: 0x66b70000 st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1 buffer tsn: 5 rdba: 0x014000e3 (5/227) … 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 … block_row_dump: tab 0, row 0, @0x1f70 tl: 16 fb: --H-FL-- lb: 0x0 cc: 2 col 0: [10] 31 20 20 20 20 20 20 20 20 20 col 1: [ 1] 42 Itl Xid Uba Flag Lck Scn/fsc Itl Xid Uba Flag Lck Scn/fsc buffer tsn: 6 rdba: 0x01800160 (6/352) TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x01800120.0486.02 scn: 0x0000.0022c821 index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120 0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121 buffer tsn: 6 rdba: 0x01800120 (6/288) UNDO BLK: xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000 * Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005) *----------------------------- uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821 txn start scn: scn: 0x0000.0022c831 logon user: 5 prev brb: 25166111 prev bcl: 0 Begin cleaning out block ... Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224 WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417 WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687 … Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow... itli: 2 flg: 1 scn: 0x0000.0022c811 Block header dump: 0x014000e3 … Itl Xid Uba Flag Lck Scn/fsc 0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23 0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 Undo header Block 두 번째 update Undo Block 첫 번째 update Undo Block BH (0x673f4b40) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x67328000 st: CR md: NULL tch: 1 buffer tsn: 6 rdba: 0x01800160 (6/352) … TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002 mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe) uba: 0x0180011e.0485.02 scn: 0x0000.0022c811 … index state cflags wrap# uel scn dba ----------------------------------------------------------------------------------------- 0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e 0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f Scn: 0x0000.0022c821 Scn: 0x0000.0022c818 Scn: 0x0000.0022c811 CR 블록 적용
  • 54. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved. Oracle Deep Internal Blog Video E-mail NAVER http://cafe.naver.com/playexem ITPUB http://blog.itpub.net/31135309/ Wordpress https://playexem.wordpress.com/ Slideshare http://www.slideshare.net/playexem Youtube https://www.youtube.com/channel /UC5wKR_-A0eL_Pn_EMzoauJg Tudou http://www.tudou.com/home/max gauge/ [email protected] [email protected]